Are you going to use multiple formats? Are you looking for a rollfilm back that takes 120 and 220? Are you looking for a roll film back that can slip under the groundglass?

If the answer to these questions is yes than it is worth the money. I've owned a fixed format (6x7cm) Sinar rollfilm back and it was superbly engineered and have me excellent service. If you get the Sinar back It is also worth the money to get an extra film cartride or two.