I have both Biokovo and Karmina varieties. I have split Karmina several times and it grows rapidly into a nice size clump. It seems to have a longer bloom time than Biokovo, but I like both. They only bloom in late spring-early summer, though, not from late spring to fall like Rozanne. They have never rebloomed in fall for me.

Neat and compact is exactly how I would describe G.Cantabrigiense and it can't be beat as a groud cover. The only draw back is the short bloom time. An other plus is the colour in the fall. Here both Biokovo and Karmina are showing red leaves now and will keep them all winter.
Leo

I have Biokovo, as stated above by others, it stays very neat and has a fairly short bloom time. I know it is often used as groundcover, but it took several years to get a big clump so I wouldn't want to have to cover a big patch with this one, not in my conditions anyway.

I have Biokovo interplanted/surrounded with grayleaf geranium. G. cinereum 'Splendens' which are even smaller (6-8 inches tall) hot pink color and starts blooming when Biokovo is done. I also have several varieties of sanguineum in the same area, but they are so new, that I'm not sure what their bloom will be like longterm.

I think you might also consider a hard prune of your Rozanne. I let them go to town in early summer, chop them back hard when they start getting sloppy, they regrow quite nicely and stay nice the rest of the season for me. Except for a few weeks in July after pruning (when lots of other stuff is in bloom) they bloom constantly from June til frost.