More time with Dad is definitely a good thing...unfortunately, more conflict between bio mom & dad is a very BAD thing. Been there, done that. It is really terrible for the kids. An offhand comment made to mom like "My room is cold at night" gets blown up into "he said he doesn't want to stay at your house because you don't care enough about him to turn the heat up." - When we didn't even know of the issue to begin with.
Anyhoo, when my (now 17) SS was little, he and his older bro (now 22) went back and forth between mom & dad's pretty much as he pleased. This was NOT the best, because it turned into them always choosing separate houses. Also, whenever discipline or chores was introduced at one home, they would hightail it to the other. When the younger one was about 11, the plan changed, and we got him for the first 10 days of each month, and then 1 evening thereafter. We left summers flexible. (Ex-wife had always insisted my husband have them the whole summer, b/c she didn't want to deal with child care issue. Anyway, this worked really well. Granted, there was a quick trip every other day to Mom's house to pick up forgotten stuff, but as long as you can be flexible about that kind of thing, it was fine. We also got him a cell phone, so that his friends didn't have trouble tracking him down - he was a very social and popular kid. It worked a lot better having him on a schedule.
The schedule broke down half way through his freshman year of high school. Our 2nd child was born, and our house was not much fun to be around for a teenager - there was little attention to be recieved, and lots more rules. If we had it to do over again, we would have enforced the revised custody schedule, as the kid's grades really slipped.
In any case, middle school was the "golden time" for this kid: He had a lot of involvement and time with BOTH parents, and got straight A's and was capt. of various sports teams etc - it really helped him shine.