10v or 20v turbo?

[docwyte at comcast.net]

Which would you go for?  I'm attracted to the higher hp of the 20v turbo motors, but wary of increased maintenance costs and reliability.  I know 225hp can be had out of the 10v turbo, but is it very difficult/expensive to wring out the additional 50hp or so to equal the performance of a chipped 20v turbo?

I'm up at 5000 ft above sea level, so what would normally be an adequate amount of power can be a bit anemic.  Well, that and my 360hp M3 has spoiled me...

-josh