Congratulations on your aquisition of 2 V1U’s (they are fantastic cameras)
The only real reason I can think of to use the sony hdv tapes exclusively is drop outs.
How important is it to you that all of your footage is good and glitch free?
After going through trials of different media, I found that the Sony HDV tapes are by far the most reliable.
More reliable than the JVCPRO-HD media that was allegedly designed for my HD100 camcorder. I had dropouts on every tape I shot with, not many but they were there.
I switched over to the Sony HDV tapes after hearing stories from many others about how great it is and how they had not had dropouts, and now I have no dropouts on my shoots.
Some people will say they use panasonic stock and have no drop outs at all. I guess then it depends on your karma/luck.