We had a 1/4" 440 around for awhile, and I have a 1" 8 track 440 sitting to my right as I type, which doesn't really get used truth be told. But when we had the 2 track (before the two ATR102s came in), it did get used from time to time.
The 440 is an interesting machine... not quite as old-school as a 351, but not a modern machine like an ATR102, either. Kind of a 'tweener.
It does have a sound-- a rather big, characteristic sound. It's got a form of that classic Ampex "larger than life" thing. Repro definitely does NOT sound like input, but I wouldn't exactly call it "lo-fi." More "euphonic." Not a lot of precision in the transport... it relies on brute strength, whereas the swiss machines rely on precision and engineering. A 440 in fast-wind is a terrifying thing to behold.
It sort of has all the attributes that make one generation of engineers relieved to no longer use tape, and also all of the things that make another generation fascinated with and attracted to tape (if that makes sense).
I wouldn't want to use one as my main 2-track machine, but it's definitely cool to have around as a "flavor." It sounds "burly." It would be appropriate especially if you're working on some period music, or a mix where you want to impart some euphonic coloration and make "technicolor." Also would likely be really cool as a tape slapback machine, though I never used ours in that capacity.
I modified ours-- I took all of the tantalum caps out and replaced them with WIMA metallized film caps where possible, and Nichicon KZ electrolytics where the films would've been too big. Definitely opened up the machine a bit in terms of making it a little more "hi fi," but perhaps lost some of its signature "grit."