I have both Otari MX 5050 Bii and a Revox A77. The A77 will not play 15-IPS, but I'm thinking some may have. I don't consider my A77 to be a pro deck, but a nice deck for 4trk. I'm guessing once you move up to 15-IPS, your out of consumer model decks (unless you find a A77 15-IPS). I went with the Otari because there are so many out there and parts are still around...plus it's a solid machine.
One thing you may want to look into if your purchasing a R2R for recording or listening to the tapes you have....make sure the tapes are 2 track and not 4 channel. As mentioned above? Teac 3340 3440 and many other 4 channel decks were used by musicians to record demos. Tapes from 4 channel decks will not play correctly on the 2trk Otari even with 4 Trk head. These tapes may be 2trk masters from a studio session and will play fine.
You mention you wanted to record. Are you recording your own music to tape? Teac 4channel may be what you want. Then can over dub and bounce tracks. Not exactly pro level, but a good starting point to get use to recording to tape. If your wanting to record your vinyl to tape, a 7.5 machine would work great. 15ips is a lot of tape to record vinyl. If you want to do 2trk masters or hit tape from pro tools, the 2 track 15 IPS would be the best choice.