I just purchased Festools RO 150 and the ETS 150/3 sanders.....but I was wondering which of their sanders would work best on narrow surfaces such as face frames. I want to get smooth surfaces where grain direction changes without risking rounding over edges due to balance problems, and I wanted to find out from you guys which sander fits the bill: the 5" RO, the DS 400 or RS400 detail sanders...I have no experience with the 6" ROS so I dont know if they are too large for this purpose. I was leaning toward the DS 400 for its corner and detail capabilities....any input would be appreciated...I dont want to buy a nice tool that will just sit around! I have not received my other sanders yet.Thanks