I have both of those mods. I keep the 30 s on the VTR because it's reasonably compact and I can carry it in my front jeans pocket without any problem. The 134 get a double thumbs up due to the "outragous factor" but If I could buy only one of them, the VTR would be the one I'd pick.
As far as switching attys goes, any difference for me has been negligible. I was a bit apprehensive buying a VW only mod and I do wish they'd made all the steps in .5 watt increments so I could maximize my vapor production without any occurance of burning. Full watt increments is just a little broad, in my opinion. Still, I love to use it.
And oh, the Cool Fire II was purchased by me for exactly the same reason as my 134. Increment on wattage are similar, though not exactly the same, at the 134 and a 16350 battery needs to be changed too often. While I own 4 of the 16350s and have no problem keeping a charged on on hand it's still a bit of a pain. I do love my Cool Fire II though.