The new 510 is more durable but if you don't switch out atty's a lot it should not be a problem at all.
I haven't gone below 0.9ohm with the non-sub contacts but used 0.9+ exclusively. Not sure how low you can go with them safely. The Veritas is tasty even with a 1.0 ohm coil (I run my Veritas single coil, as dual did not give me as much flavor).
Yeah I usually party between .4 and .6 depending on my building mood. Right now I got a .41 and a .53, wouldn't mind using a higher ohm though.
Can you use VTC4's in reos? Or are the strictly made for AWs?