I had a customer's DV-507 and his XV-1s for about 6 weeks. He wanted me to break everything in for him.
I don't know how this relates to the 505, but there were two usability issues which immediately disqualify it from consideration for me. Both make it easy for the owner to unwittingly trash a cartridge. The first one can be fixed (which I did for my customer) - to replace the nylon tipped set screw (gross VTA height adj) with an Allen keyed steel tipped screw. I realize why D-V chose the nylon, but the problem is that if this screw slips, your cartridge is at great risk, because there is limited upward travel of the headshell. It's very scary.
The second way you can lunch a cantilever is by being temped to use the very nice VTA adjustment scheme to adjust VTA in play (don't do this !!). You fine adjust the VTA by loosening a lever at the base and rotating it one way to raise and the other way to lower. It's a very slick design, but if you unscrew this lever a couple of turns, it disengages from the helical slot and down goes the tonearm on the cantilever. If you're aware of this, it's really not a problem.
Thirdly, the cantilever can only clear the LP by about 1/4" because of the limited upward travel of the headshell. This scares me too.
Having said all of this, the DV-507 was a reasonably nice sounding tonearm with the magical XV-1s riding on it. Truth be told, I think it was a bit too laid back considering that the XV1-s errs on the side of sounding slightly forward sounding. So, if you end up with one of these arms, don't get a cartridge that tends toward the lush side.
Cheers,
Thom @ Galibier