Ortiz actually isn't all that bad defensively believe it or not. He's not going to win a gold glove, but he can hold his own in national league play. I'm not too worried defensively, although the surface at Coors field tends to play a little faster than at Fenway.
I'm more worried about losing Youkilis' bat in the #2 slot. He and Pedroia together have been absolutely incredible the last 4 games. Breaking up that table-setting duo is gonna suck, but hopefully we go into Colorado with a 2-0 lead so we'll have some breathing room just in case it does come back to Boston for 6 or 7.
You may even see Youk play a little 3-bag with Francona putting RBI machine Mikey Lowell on the shelf (at least to start a game) with JD Drew slipping into the 5 hole vs the right hander Jimenez. With Jimenez being a rookie, it might be a good idea to get Youk into the 2 spot to fight off some pitches and work up the pitch count. You saw what Youk and Pedroia did to Carmona in game 6...I was there that game and it was awesome.
Either way you look at it, the sox will be losing out offensively playing on a National League stage. Pulling Mike Lowell isn't exactly like putting Alex Cora in for Julio Lugo, but I wouldn't be all that surprised if Francona opted to sit him to start game 3 in favor of Youk at 3rd, which would get Drew's left handed bat behind Manny against Jimenez.