Not professionally, but I owned one for about a year in the mid 1990's. It was sold simply because it didn't fit into the workflow easily. No MIDI, refused to sync to anything properly, weighs a flipton, the step keys were iffy and the worst bit is that the analogue side was crap i.e. it used to drift terribly after it got warm. Programming was pretty good though so i'll give it that.

Access Virus is a rip off. I had a KC and it was no better than a Novation KS6 at a fraction of the cost. Fortunately the scene I was in grew out of the Virus eventually. Not sure about a monotron - horrible sounding feepers. Seem to be trendy but not particularly musical.

I very much doubt many Stradivarius' are actually played. They are like art. The value is subjective. Personally I hate the whining things and would rather use them to smoke some cheese with (this is sarcasm) :)

For me, it's a matter of pragmatism. My Triton sounds pretty good (not too digital) and saves lugging a crap ton of kit around. If it doesn't do something, I'll sample something that does do it and I'm sorted.

NB I was a session keyboardist in the goth/industrial scene for a number of years (also known as unemployed student) so I have some professional experience.