with ML2032 (e.g. from Conrad) it works fine... (you may want to charge the new battery for a few hours after installation with the keyboard switched off).
I replaced the rechargeable button cell with a normal 2032 button cell before the question was asked here - so at least 7 years ago. It's been working without any problems ever since (and nothing has exploded either...)
I got my dusty K750 out again and am now at the same point. I was able to remove the battery once, but now I'm looking for a replacement. I'll have a look around, are there any recent experiences?