I bought my OASYS 76 in 2007 and the only thing I can say as far as any troubling issue(s) I've had is with the rubber fader knobs which developed a sticky feel to them after about a year to a year and a half. All in all, a small problem considering what a punch this thing delivered back in 2005 or whenever it was first released in this form. Replacement knobs fixed the issue very easily.Did the OASYS have this kind of failure rate & user issues?
I just replaced the CR-2032 "watch" battery this year after the message appeared saying the voltage was getting low, but other than the aforementioned knobs, the tool has been rock-solid. That said, I know someday that something catastrophic might fail like the motherboard or what-have-you, and if no replacements are to be had, I would moan and wail and cover myself with sackcloth and ashes while sitting on an ant hill!
For that reason, I am interested in getting the newest KRONOS 73 in the Soundworld. No, it will never have the IMPACT on me that the mighty O delivered (and still delivers!) but at least I would still have those gorgeous Programs/Combinations and KARMA I have come to love to keep me occupied.
I will add that the OASYS was ~$8000 (in 2005 dollars no less), so I would guess that the old adage "you get what you pay for" applies here. Still, you gotta figure that the R&D had to be much lower for the KRONOS since the main scheme came from the OASYS and it would have been great if KORG had worked out some of the chronic bugs and issues before putting the original KRONOS on the market.