Robert - European washers are tested using a load of cottons to the maximum load capacity of the machine (nowadays often 6-7 kg). As Mike said, an 1800rpm spin will average about 43% RMC, 1600rpm 44%, 1400 50%, and 1200 generally gets about 53-54% RMC.
In terms of spin time - as you probably know I have 2 1600rpm washers; both the AEG and the Miele. The AEG will maintain 1600rpm for 4 or 5 minutes, whilst the Miele spins at 1600rpm for 2 minutes at the end... and I have to say, although I haven't tested this scientifically, that I haven't really noticed a difference between stuff that has been spun for 1600rpm for 4 minutes and laundry that's been spun at 1600 for 2. I did read somewhere that, for European frontloaders at least, that the speed that gets the most noticeable moisture out of laundry is 1100rpm or so, whereas any higher speeds extract little more out though I have noticed a big difference between using 1600 and 1200rpm.
The spin profile on my AEG, is a long 12 minute process (and quite painful!). Distributes, 800rpm burst, back to distribute speed, 1 minute 800rpm spin, back to distribute speed (no tumbling), then it profiles through 800/1000/1200/1400 for about 2 minutes, then maintains 1600rpm for 4 or 5 minutes before slowing down. The Miele does it somewhat quicker - it will do 0-3 bursts depending how heavy/absorbent the load is, and will then start the final spin at 6 minutes - profiling up through 400/600/900 to 1200 in the first minute of the spin or so, 1200rpm for 3 minutes, then for the last 2 minutes the drum speeds to 1600rpm. It seems to do just as well a job as the AEG's elongated spin process, so I think with frontloaders at least the key stages of extraction are within the first few minutes of a spin - and spinning any longer than necessary doesn't really extract more water.
Anyway that's enough of my babble! Well done on the tests, they're very interesting and have got me hooked to this thread!
BTW - unfortunately the AEG is now out of service, but I could always perform a similar test in my Miele when I have free time, perhaps at different speeds too, to give a frontloader perspective? Mind you the towels won't be the same weight but if we're working out RMC values it might give a general idea.
Jon
P.S. - The 30 minute spin on your Unimatic may seem frightfully long, but my nana's newer machine takes 20-25 minutes to do the standard final spin cycle!