I don't know if i would do that.
Koshansky has a lot of power, but some question how much average he will be able to hit for. He is too slow for the outfield and he is blocked at first by helton. Right now it looks as though Helton will veto any trade, so Koshansky may never get a shot in colorado.
Beltre on the other hand has tons of pontenial, but is still very young. He could be the next Carlos Beltran, but it is just as likely that he will be the next Joel Guzman (not living up to high expectations after a lot of hype). He is interesting but is years away.

Tough delima, you have one kid who has proven nothing and won't help you for a long time, and another who is blocked until he is 30.
"I do not think baseball of today is any better than it was 30 years ago... I still think Radbourne is the greatest of the pitchers." John Sullivan 1914-Old athletes never change.