The thing that's making me hesitate on the RF-35's is actually the size, although they're only slightly bigger than the RF-25's. The room they're going into doesn't leave me a lot of space for speaker placement. It's more of a scale issue than anything else--the speakers could wind up dominating one side of a smallish room.
By the way, these will be paired with a Marantz SR-18. Funny thing is, I started out thinking about RB-25's, then the RF-15. And now I've worked my way up to the RF-35. Where will it end?