He'd be going from what is still the best hitters park in MLB (it's not what it once was but it's still #1) to the park that has ranked #24 in runs scored over the last 3 years.
He'll go from the team that was 11th in scoring last year (with a similar lineup) to one that was 18th last year (with a similar lineup except for GMJ).
He may move up in the lineup, but LAA usually bats Vlad 3rd so he'd probably be Vlad's protection not the other way around and move from 5th to 4th in the lineup. That's not a huge change.
Hitting around a good hitter is great, and Vlad is one of the best... but he has Helton and Holliday in COL. I think that's a wash if not an upgrade over Vlad/GMJ.
His splits indicate he does hit much, much better in COL than away. Even this year while he's struggling he's hitting 40 points higher at home. And you're happy to take that away?
He will run more often in LAA, so that will be good but his HR will drop, his BA will drop at least a little (as due to the spacious CF in Coors even line-drive hitters benefit) and his R and RBI will probably drop, if not at least stay the same.
Facing the Rangers pitching will make any one a better hitter, but since he's not a big base-stealing threat I don't think the SBs will go up enough to compensate for the lowering of his HR even if the other stats stay the same.
Just don't see why this move excites anyone except AL-only owners.