I've always enjoyed playing Violin basses, but there are a few things about them that bug me; limited tone, intonation, Neck dive, etc. But it crossed my mind that much of this could be fixed. I did a search, but didn't see much of anything about modifying or upgrading these basses to have more modern features, like a tune-o-matic bridge and a traditional tone knob, NS strap horn, etc. Is anyone doing this? And if so what have the results been?

I have a couple of them. I like them; they're fun to play - and I can play them with no problem. And, for
some of the music I like to play, they work/sound just fine.
But... I've accepted the fact that they (like me) are relics from a time long past, and that no matter what I try to do with/to them? That's where they're going to stay. Fiddling with the hardware, electronics, and pickups is all well and good; if that's what you want to do. But, it's really just putting lipstick and rouge on a pig. The inherent flaws in the basic design are there - and will stay there - forever. Years ago, I spent a lot of time - and a great deal of money - on a '67 VW Beetle. It was a lot of fun, and I don't regret it. What I wound up with was a very expensive little car that would go down the highway at about 165 mph, but... it was
still a cheaply made, kinda flimsy, '67 VW Beetle. It just went way, way, too fast... It was
never going to be a Porsche Turbo Carrera, no matter what I did to it, or how much money I spent on it. If you want a modern, "cutting edge" violin bass? Your only real option, IMO, is a custom, solid body, violin bass - shaped object....
