I've heard a lot of diversity in SID music in the 80's, let alone the 90's. The replay routines were bespoke to each composer. As an example, Galway didn't use drums much at all until he was playing samples sounds. Stylistically the composers, I feel, were very different. Unfortunately some of the composers tended to write the same tune over and over again, but that's the case these days too. You could argue that as time goes one, most styles are invented which people use as inspiration to base their own music on? Back in the early SID days there wasn't really a lot of good electronic based music to listen to. Jarre, Tangerine Dream, Larry Fast, Tomita, Carlos, Vangelis etc.... but even in the 90's you started getting swamped for choice.
I've got a lot of respect for these guys. I tried so hard to write decent C64 music, keeping in mind I was 11-15, but I could not get my head around the limited software available - and ended up using ElectroSound. Jeroen Tell however, a year older than me, was writing superb stuff at the age of 15.
When you open your mind to what trackers can do, you work around the limitations. Most people just write in 4 beats to the bar, but you can swing, do 6/8, whatever you like. You can go completely mad if you like - check out some of Heatbeat's Amiga stuff like https://soundcloud.com/demoscenedelight
cykl0pedia - samples yes, 4 channels yes.
And the SID is one of the most flexible 'chiptune' devices out there, like everything, it's what you do with it.
m