Target Field, with its apparently closer fences and limited foul territory, would project to have a higher run environment than the Dome, if all things were the same. But, we have weather to deal with now.
Now, I cannot project how the infield will play, or how bouncy outfield walls are, or Gardy asking for the dirt in front of the plate packed down to resurrect the Baltimore Chop. However, I can make reasonable estimates for the fence distances and heights. And oh what fun that was.
So, how does it really compare? The field dimensions listed for Target Field: 339 feet LF, 377 LCF, 404 CF, 367 RCF, and 328 RF, do not compare well to the Metrodome's dimensions: 343, 385, 408, 367, and 327 respectively. However, that is just five points in a 90 degree arc. Plus, the listed dimensions for the Metrodome are wrong. 343, 408, and 327 are right (probably). 385 and 367 though?