I find the combitank great. Yes it has slow drain and fill times, but in practice using dev times over 10 mins, I have never had problems. I get very even development, but keep agitation down, which helps I would think. Do a search and you will find some tips from me and others about how to make them work better for you. I have two and would not be without them for 5x4. Some of the plastic components are a tad fragile and one has to be careful with these bits (film retainer). Mine have had 3 years use and probably have many years left. Loading is very easy once you get familiar and it is not tough to start with, tho even with the film loading guides, one can miss the innermost slots to start with. I know some say only do 4 sheets at a time, but now that mine's is bonded perfectly square and rigid, I do 6 with none popping out of runners and even development.
Tom