Our neighbor just had to replace his. Evidently, they've changed the code on the PVC venting pipe (the old stuff had some sort of semi-flammable something inside of it). It was going to cost thousands of dollars to do it to code so he just hired some independent dude to install it using the existing vent pipe.
Of course the new water heaters are quite a bit different height than the old ones. (Learned this with the last one 1 1/2 years ago). I don’t like brazing for house stuff otherwise I would do it myself. Last one was 1100 with no labor cost. (This is when he asked for a favor and I ended up 20 miles away for the whole day.)