Thanks all.
Two grinders is not in my playbook and single dosing using one grinder seems a reasonable option I will consider.

One way (cheating?) I found is that I can pre-grind a projected weekly amount of decaf and store it in a closed container.
I can dial the grinder so in day 1 extraction is fine by using 18g in a 20g basket.

I can dose a bit higher (up to 20g) as the decaf ages over time, in order to control the flow and make up for loss of aroma during the week.

The main beneficiary of the decaf (wife) will likely not feel a significant difference over the week so I am going to give this a try.

We solved this problem for us by single dosing with pre-weighed blends of regular SO and decaf. Total pre-weighed dose is completely ground out in the grinder and re-weighed in the portafilter. Although the shot is timed, it is cut off based on extraction weight of 2 to 1 ratio of espresso to ground coffee. Timing is only used as a guide to determine whether next shot needs adjustment in grind fineness or weight.

Line level preinfusion using a naked portafilter 'fine-tunes' each shot to its own 'perfection'. Grinder readjustment is super easy with our grinder; we have only one. It is constantly readjusted as we alternate between regular and decaf between each shot. I drink regular coffee, wife drinks decaf.

Our shots are excellent in our estimation and our guest as well.

YMMV

travis_rh wrote:Jeff's mid-level hand-grinder idea is probably the best.

Otherwise, I might:

• Sell the Vario, buy a single-dose grinder like the Niche, pre-dose both my regular and decaf into labeled tins, and get used to dialing in and brewing a single dose at a time
• Pick up a hopper with a shut-off (or two) and simply remove the entire hopper, grind through what's in the grind chamber, swap to the other coffee, and vice-versa
• Skip the whole buying and selling of grinders and simply pre-dose both my regular and decaf into labeled tins, and get used to dialing in and brewing a single dose at a time

you can get baratza's single doser hopper for the Vario. People seem confused with the SD hopper thinking it's only good for the Encore but it's good for most of their grinders except the Sette I think. I have one for my Vario and I can confirm it works fine. It has a great flexible dosing cup that doubles as a lid to the hopper (it can also triple as a bellows). upgrade the Vario with the BG burrs and you've saved yourself a bunch of money. There's nothing wrong with the grinder and people still rave about it. I don't use my vario for espresso and find I can never quite get the grinder fine enough. The Niche is a great grinder but if you're switching to single dosing it will be the same amount of work single dosing with the Vario. Or you could buy the Niche and keep the Vario too, keep the hopper full of the beans you use the most, and single-dose with Niche.

One grinder, two coffees, two portafilters, two baskets, two doses

Well it works for us with no grinder setting change needed.

Regular espresso uses either an IMS or VST 18 basket with 19 grams of coffee.

Decaf uses an Espresso Parts basket with more restrictive flow and 20 grams of coffee.

Could you dial in the decaf more - probably. Does it matter to me, no. This works so much of the time.

This was an accidental discovery when I got a second portafilter for when we have guests and I am pumping out multiple caps.

Funny timing on the post this am, since I blended a regular (Ethiopian Wush Wush) and decaf (Colombian Palo Rosa Sugarcane) and put 19.5 grams in the decaf set up. Sipping this espresso is great.

Not the lowest cost option if you don't have a second portafilter handy.