If you have used 'groove boxes', either one of the diamonds in the rough or their annoying ilk, then you may understand just how unique the Yamaha groove-style sequencers are (including the QY series, though I never owned one). Amongst the throngs of seething 16-step rhythm and bass machine style sequencer lovers, I dream of an evolution of pattern based sequencing with scenes for morphing sets of controllers. I used to use these weekly to create experimental ambient and Reflex-like braindance music. Eventually, I sold these things because I had sort of used them up and I like change and flux and don't want my tools to define my music.
Ableton Live is actually very much like these yamaha sequencers. Similar to these pattern/section sequencers, Live has a linear 'song' mode and the ability to trigger sets of phrases which play sounds on tracks (called scenes in Live, patterns on the grooveboxes). Ableton also adds the only useful abilities of the Roland phrase samplers (SP-404, SP-808) and MPC samplers, to trigger samples and sequences live or out of sequence. Luckily, it inherited neither the horrible effects nor the ridiculously low polyphony of these Roland toys.
I have observed that the feature sets of electronic music devices are basically locked specifications. They are set per device or per application and then never really change in major ways. Too bad. Right, right, I know.. just use max/msp.. yeah totally. I love what is possible with PD and Max and Audio Mulch and Bidule and other visual programming paradigms. Though I may just be a sucker or lazy or not wanting to reinvent the wheel, I immediately gravitated towards Live when it was a baby little version 1.0. I think of Ableton to Max/msp as I do OS9 and previous Apple OS to unix. In those analogies, both unix and max were very powerful but slightly painful for those without enough experience to create and maintain custom tools while os9 was better looking, smoother, and required low effort to learn. Back when os9 was around I was baffled by unix and idolized hackers and also couldn't afford Apple computers. Now, OSX is tightly integrated with unix and it runs Max for Live. More than a win win that's a win-cubed. Blah blah blah..