I use a 3 stack 35mm stainless daylight tank and put 2 4x5's vertically. They standoff the sides nicely and have had no uneven development. Mine holds 1L of chemistry, and I fill to the top (I use rodinal, so its cheap, and generally get 4 - 6 slides out of a liter)
I'd be one that swears AT the tray dev. method. too many scratched negs and uneven Dev.
Plus, 15 - 30 minutes in the total dark isn't so much fun by yourself.