[My current 55 set up is sumpless with a Remora Skimmer (so I voted sumpless) but my new 105 is RR so will have a sump. I feel that I have done pretty well with out the sump. The biggest challenge was keeping the scum off the surface but I solved that by using an Eheim surface extractor hooked up to my Remora. Man I have to get a decent camera and post some shots before I tear this thing down.]