O1 w fd has waveshaping feature unlike newer synths which can make sounds warmer unlike newer korg synths.bass and mid sounds cut very well with full punch in sequencer driven gigs (it's easily audible compared to sound canvas sc 88 pro board).it was THE workstation of early 90's.yes it's no GM.don't take high density disks(there is a work around),unsaved seq data will be gone when the pwr is off,etc.
but it's built like a tank and has combis(8 progs),can use PCM cards-still lots of 3rd party support ,less poly than g1000 but sounds are much fuller,no short or similar samples like g1000,and ofcourse better synth power,and control.
but they are in different catagories.one is workstation,one is arranger.I used to had xp 50(jv1080 board which blows g1000 's sc 88 pro)and O1w for years with live band,believe it or not when you start to solo my hands are on O1,yes piano is not as good as roland' but most sounds are and of course keys are also well made.
the good news is O1 now is 400-500$(xp 30 too)even trinity is 600$ these days.if you have a good versatile arranger like 2K ,yes combination will blow g1000.
don't forget this is not roland-korg debate.
this is 01w/fd + psr 2100 vs G1000 debate.