Jeff, I don't think there's anything fundamentally wrong with what you're saying, but like a lot of other people who have posted on this thread, there's a slight misrepresentation of what has been said about descaling.
No one suggested that the descaling process, if done properly, harms the welds in a GS/3. It was Roberto from LM who expressed concern that use of soft water over a period of time might damage the welds, as it apparently did in the case of an owner in Isreal. But we have no idea what the composition of that water was. He didn't say descaling hurts the machine. In fact, he said to use water with 70-80 ppm hardness, which is consistent with the minimum coffee experts recommend, and said to descale the machine once a year. That's straight from the factory in Florence.
However, there are no recommendations or instructions for descaling in the GS/3 manual, other than draining the boilers once a month. When I asked LM USA about it, they said don't descale the machine, just drain the boilers once a year. Seeing as how Seattle, where they live, has very soft water, and even the manual says to drain the boilers once a month, I found the recommendation less than satisfying.
As for Chris, he (actually Mary) told me the same thing they told you: 3 grains hardness max, don't descale, bring the machine in after a few years and they'll take care of it. Chris would be the first to admit he's not a coffee cupper. He sells and services coffee machines. From his perspective, a slightly more tasty cup is less important than a working machine. I have no doubt his techs have received machines that were shedding metal because they were designed improperly or were descaled improperly. Different perspective.
But when you look closely at Chris's recommendation, it's 52 ppm of hardness. Roberto's recommendation was 70-80 ppm. We're not talking about RO at those levels, and they're consistent with what Jim Schulman recommends in his water FAQ. Heck, according to the FAQ, if your water is very alkaline, you're going to get scaling in the steam boiler at 50 ppm anyway and will have to descale. So, what I'm saying is that the recommendations from Chris and Roberto aren't entirely inconsistent with expert recommendations for taste, and are likely to require descaling. So be it.
I think there's been a misimpression that I and others are afraid of descaling or don't want to be bothered with it. That's not the case, at least for me. I'm willing to do whatever it takes, provided it's safe for the machine. It's true I've been concerned that the company that sold me the machine, and the company that distributes it in this country, both discouraged me from descaling. But that advice has effectively been trumped by the factory's recommendation to descale once a year. If they recommend it, I'm sure it's safe.
That said, while I've descaled cheap coffee machines and water boilers, I've never descaled a really expensive espresso machine. Can you blame me for being cautious about it? What I'd really like is a set of instructions from the manufacturer telling me exactly which product to use, exactly what concentration, and exactly what procedure. I find it unconscionable that perveyors of expensive equipment like this, that likely
requires periodic descaling, don't provide instructions for how to do it safely. This would be like the owner's manual of your car not providing information on how to change the oil.
[I realize manuals are not the answer to everything. The GS/3 manual says to use a
tablespoon of detergent for backflushing. Even I know that's a typo!]
I appreciate people on this board telling me it's no big deal, etc., etc., but no one here has offered even general guideliness for concentration, how long to let it sit in the machine, how long to flush, etc. I suspect no one really knows exactly what these parameters should be for a GS/3. That's why I want to the people who make the darned thing to tell me! For heaven's sake, they should include a packet of descaler with the machine, just as they include a container of detergent for backflushing.
On taste: I've taken a lot of grief for using 30 ppm water initially with my GS/3. I thought it best to do that until I could learn enough about water treatment to optimize taste and minimize scaling. So what if I go a week or two with less-than-optimal coffee while I do the research? Sheesh! As it turns out, somewhere in the middle of this thread I switched to 70 ppm, and this week I've switched to 50 ppm. I wanted to see if I could detect any major difference (there are so many other variables going on, like different grinders and coffees, that I can't.)
Oddly, some have jumped down my throat as if I'm using RO. In fact one poster derided the idiots in this thread who use RO. I don't know where any of that comes from.
It's amazing to me that so many people consider me an idiot, and they haven't even met me (perhaps they would have better cause if they did

) They seem to think that I'm cowering in some corner, too afraid of descaling to use harder water. That's absurd. I'm simply being cautious until I learn more. I have very hard well water here, and I've seen thick sheets of scale floating around in a Japanese water boiler we used to have. I do think about that stuff coating the steam boiler/heater or building up in the GS/3's very small gicleur. Until I get a better handle on available options, I'm going to play it safe. I think I'll survive even though my coffee may not yet be the best my machine can produce.
I'm probably going to plumb in, and will likely use a cation system. Many experts on this site use such systems, so I'm reasonably confident that I'll get good taste. I also assume that I'll need to flush the boilers regularly and descale probably once or twice a year.
As I posted in another rant, I get really tired of people telling me that I'm not concerned enough about taste, or that I'm a dilettante. The questions I've asked about the tradeoffs between taste and scale, and how to safely descale, are legitimate. I don't need a lecture on what my priorities should be.