DON T. - I think I'm going to agree with MATT here. Since You have the 44" deck already, if You have the correct mule drive I'd go that way. The only other deck I would consider would be the 50" deck. They're a nice sized deck for an SGT since an SGT is 43" wide overall.
I'd have to check the parts look-up but last I knew the waterpump bearing insert was $80-90 US, I knew there was an alternate replacement bearing but haven't researched it yet, but I need to replace at least two on my 50" deck before I start mowing this spring and I'll know all about them by then!
The 44" & 50" decks do have problems with the rear gauge wheel brackets causing cracks next to the welds, and during hard usage the whole housing can distort causing uneven mowing. But it's been my experience the blades on the 44" & 50" decks last longer, and all three are the same length, and Gator blades are available for both the 44 & 50 in. decks.
Richard C. has reinforced his 44" & 50" decks and as always, supplied the forum with MANY pic's with details. MTD also improved the decks in a similar manner.
The only complaint I have with my 50C deck on the 982 is that with the deflecter on the discharge chute it's too wide (over 60")to fit in several places in my yard. I cut the deflector off my 44A deck on the 129 I had so it would fit between the wheel wells in my pickup box for hauling. Maybe not the safest thing, but I normally keep my feet & hands where they belong, away from moving objects. And after that it fit EVERYWHERE, mowed smooth, and I don't ever remember replacing the blades in the 15-16 yrs I owned that mower. Not sure if they were hard coated, pretty sure they weren't, but even hitting the occasional rock the blades only needed resharpening 2-3 times/year being my primary mowing tractor on two acres. Wish I had that deck back, but don't miss the 129 all that much, Not a bad tractor, I just had a WHOLE lot of money in it and it needed some more spent on it and I got a good price for it and needed the room for Dad's '51 M in the shop.
I want to put a wider deck under my 72, and a 44" would be my first choice. Just not sure when that will happen.