How can this be done? Voices start at different times and consist of different audio going through modifiers that have to be unique for these same reasons. And each Element, regardless of its configuration with others in any particular Voice, has (must have) its own set of modifiers. Right?There are up to 4 elements with each element sharing a filter, amplifier, and modulator settings. Every new element brings it's own settings for the filter, amplifier, modulators, etc... What you were thinking of is voices, yes they're all sent to their own filter and amplifier etc... But those filter and amplifiers are grouped together.
Aaaaaanyway, I can fully agree with your other conclusions, of course. Whichever way we slice it, the SY77/TG77/SY99 – and, I imagine, particularly the latter with its more advanced effects – do a heck of a lot for machines of their time, and even for today when one considers that they’re still unrivalled (again, particularly the 99 ).
As for prices, Clyde has posted that the SY77 was originally marked at $2995 and the SY99 $3995, and he was following the range from its earliest beginnings, so he’s bound to be correct. On the other side of the Atlantic, I have the issue of Sound on Sound with part 1 of their two-part review of the SY77 here – interestingly from early 1990, not mid-/late-1989, suggesting that it arrived quite a bit later on our chilly shores – and it lists the RRP as £1999. I think I read elsewhere that the SY99 was £2999.