Just this past weekend I developed three rolls of 120 -- one in a Paterson, and two in stainless (same tank, at the same time). I don't find a whole bunch of difference in loading them. The Paterson uses more liquid for the same amount of film, but not a bunch more -- 500 ml for 120, compared to about 920 ml for two rolls of 120 in my tall stainless tank.
My personal preference is for stainless, and I'll use that unless, like this weekend, I have one roll that's a different film from the other and want to load them all in one sitting, or have more than two rolls of 120 to load. I don't like the large free volume inside the inversion cap of the Paterson, which completely uncovers even 120 during an inversion (though with the Paterson design, it's likely not a big problem in terms of surge marks or bubble production); I'm slightly concerned that using the same exact technique as in my stainless tank will result in stronger agitation effect because of the huge amount of liquid movement, and push up my contrast compared to my low agitation process in stainless. I also don't have a second reel for my Paterson, so 35 mm with a partially full tank runs the risk of the reel working up the core and leaving the film partially uncovered.
So, with my particular needs, I prefer the stainless -- not because of anything to do with loading, but because the tank design and small free volume fits my technique.
