I've got several bikes with Shimano, because they came that way new, and I use SRAM on almost all the bikes I build up.
I am not sure what people mean by clunkier, I have found shifting on my Force set ups to be fast and positive, further down the range things can get a bit more vague and a well worn set of Apex shifters I have seem to need to pull an awful lot of cable, regardless of how I set them up. Sram can also be a little more fussy to set up, needing very tiny adjustments of the rear mech to get shifts perfect, but, once set properly they very rarely need to be touched again.
I like Shimano too and certainly ranges like 105 can be a bit more slick to live with that the comparable range of SRAM.
I have never has a slightest issue moving between bikes, maybe the occasional nudge on a SRAM brake lever, but it is kind of like moving from an auto car to a manual, you just change technique with the bike.
My personal preference is SRAM, I just like the way it works.