this does happen, it happened to mine. how bad it gets I think varies- mine is still usable but its obnoxious and I just haven’t gotten around to doing the fix, maybe this winter finally… that said, its readily available parts, nothing obscure, so if you have some DIY confidence you can do it yourself or should be pretty cheap to have a tech do it when/if it does happen.
@wheelersounds sure, you can change things real time, either with the control knobs/menu or with midi control. you can get a lot of real-time like motion/randomness/etc also using the mod matrix, arp, and and math functions. I’ve made lots of very organic/evolving sound patches on mine as well as ones where hitting just one button with a midi CC drastically changes the sound.
another thing to consider when getting a used blofeld is its worth paying a few bucks more for the desktop unit if it has the sample license installed- unfortunately Waldorf still charges $100 for that upgrade. but if you have it or get it you can also get even closer to replicating the sound of a lot of other rompler/rack classics since you can usually find the waveforms either for free or very cheap.
I used to have an EMU XL-1, wish I had kept it… I never had it but the boxes like the XL7 look like great options for people who want full sequencing OTB and without tons of other hardware. plus, between all those units you can swap the ROMs around, and again not as old. I was working with someone who wanted to use some older EMU Proteus units for a project/tour… one had a dead power supply which while available costs more than the synth at this point. the other I said we should get the battery replaced before relying on it since the memory will crash/corrupt. guess what happened an hour before the first gig on the tour?