I use a Nova handline or combitanks for 5x4. One combitank fills in 25 second, but the other takes nearly 50 seconds??!! With normal dev times of about 10 or 12 mins, I have never noticed uneven development and that includes using staining devs. Disconcerting as the slow fill times may be, I have had no issues there. The only prob was with the negs popping out of the grooves once in a while; which I solved. It was caused by the whole carrier not being laterally rigid (due to poor moulding accuracy) and the top clip which presses down on the film being too tight (so when the film got wet and soft, it bowed more and slipped out of the grooved under the pressure. I fixed this by using glue to fix the carrier perfectly straight and rigid and ensuring that only the minumum pressure is exerted by the top clip thingy. Since then 100% success, daylight convenience. The only prob with the slow fill being that when using tanning/staining dev the repeated rinses, reimmersion in dev etc all takes time.