It depends a LOT on the length and action you are looking for. I'm not familiar with Rob Carpenters work, but for the record I haven't heard anything negative. Bob Summers comes from the MI school of Bamboo builders who basically owe thier roots to Dickinson and Young. Bob worked in Youngs shop fore several years before striking out on his own. The only issue I can think of with Bobs rods is last I saw his waiting list was about six years and he's getting up there, consequently second hand Summers rods tend to sell for about 50% more than new ones.
As far as models, Summers Midge (based on Young actions) and his 725 are real sweetspots and among the best actions of modern boo rods. Bob's rods tend to be fast with a lot of reserve for Bamboo and are great casting tools.