You ought to at least give it a try. I love my all-steel MkII as well, but the MkIV is also a nice shooting gun, alloy-framed or not. Mine did have some issues out of the box, but with the help of some Volquartsen parts I have it running pretty well now.Not a fan of whatever non magnetic metal the new ones are made of. My MK IV is unfired in the box after I figured out the frame was not steel. Just picked up a MKII on here and Love it a great shooter and all blued steel.
While I don't really mind the takedown process for the MkII, the MkIV does make it quicker and easier to swap uppers at the range. I've got the threaded one, a 5" Target, and a 4" standard with a pencil barrel. Volquartsen sells takeoffs for next to nothing on their website.