Teme, here is what insight that I can give you on these machines. I am sure that others will comment:
1) Are there any specific years of manufacture that are preferable over another? If so, why? I.e. I assume that over the long production lifespan of the Cremina there must have been some changes to the spec over the years (as Steve mentioned)?
The machines remind me a bit or Porsches where they have maintained a similar design theme over a very long period of time, and have slowly evolved. The manufacturer actually has a very good site on their machines including their technical specs:
http://www.olympia-express.ch/if you go to the support section of this site you can see the technical specifications for the 67, 96 and the newer 2002. In looking at the schematics you will see the same basic design resonate through the line. The 67 is the earlier and based on year you will see some changes to the steam wand, switches and bottom plate of the machine. With the 96 you get a pressure valve with some minor enhancements and there were significant changes with the 2002.
2) On a related note, I am even thinking of the possibility of going for a new one (I do not rely on my skills enough to embark on a restoration project like Steve's): are the new ones superior or inferior to the older ones? Having a new machine eliminates problems/needs for restoration and they come with some rather attractive accessories. Furthermore I find the black color scheme and the boiler pressure gauge appealing. I would need to save up for quite some time to be able to afford one, though. The price of a new one is really quite steep...
If I follow my Porsche analogy, newer models have many improvements over the older ones...but many will take a 1973 911s over a 1996 996 any day. On the Cremina, the newer 2002 does have some improvements over the older models and are a bit more complicated and some may say the older ones have more charm...depends on your likes. The key differences that I can see on the newer one are the following:
1) Powder coat vs. Wet-Coat. Visiting all the trades this week, I will use their lingo. The 67 has a painted case whereas the new ones are powder coated. The nice thing is that the paint makes it easy to remove on the older ones should you not dig the retro Brown, Harvest Yellow, or Burnt Orange that I have seen.
2) Boiler construction: Stainless 314 Steel on the new ones vs. Marine brass on the older ones. I know I said that mine was Stainless due to the shiny exterior, but you will see in my next post on the reconstruction that it is truly brass.
3) Heading element: Stainless steel on the newer one, copper on the older ones.
4) Pressure gauge on the newer ones
5) Cooler ready light on the new one
6) Changed boiler cap with built in anti suction device....
7) and finally it looks like on the new one that they have changed the piston design to make it multi-parts. Possibly to make it easier to change the gaskets.
I am sure there are some other minor changes, but there are a huge amount of base similarities along the whole line. I have not been able to find any information on desirability of those produced from 1979-1992 while the original factory was owned by Luigi Bresaola, so I don't know if there is a mystique around these older machines like pre-AMF Harleys or pre-CBS Fender Stratocasters. After I finish my restoration, I will surely start this rumor to raise the value of mine to cover the costs.
Your questions 3-5.
The Olympia machines are very well made. I am sure that this drives a significant portion of the cost. The drip tray will support my weight... all edges and metal work is perfect and their castings are beautiful. All lines are hard lines and there is just quality throughout. This work does not come cheap. They are one of those rare machines whose design point was a significant life of performance. The Elektra is much closer to this than the Pavoni. The Elektra has very good guts, and if well taken care of will last a very long time. The Pavoni, which I love, does have its weaknesses. I have what many feel is one of the better ones, but it has cloudy site glass, rusted tray, third Bakelite handle replaced etc....but I can make a great cup with it.
You will not scald yourself on the cover of the Olympia and I really like the footprint. I will do some side by side shots when I get it finished with the Elektra and Pavonis.
With regards to shot performance, you should look at Dan's posts on this since he is the only guy I know and trust that has used one of the new ones. Time will tell on mine once together. There are a few little design tricks that I am interested to see how they effect the shots that I will do a future post on. Dan will be the man on steaming. I think Dan has done great milk on all three machines.