I have a new 390 on my bike now. I had a 550 and it only lasted 7+ years and about 175,000 miles.
I bought mine from the GPS Store. With the TPMS package I basically got 1 monitor for free.
GA01186S Garmin Zumo 390LM Tire Pressure Monitor Bundle 1 $764.99 The TPMS can be used to monitor up to 4 tires. It can be used on trikes & MCs with trailers. The monitors are not numbered until you put the labels on them. They can be set up for any pressure you want. You set both the max and minimum pressures where YOU want them, not some percentage. It works very well and even graphs and records the pressure. It's also not intrusive on the GPS screen unless you have a low pressure. To check pressure you need to change to another screen.
I did not want to spend this much on a GPS but now I'm happy that I did. I don't do baggies so that was never an option. The unit works. Curvy roads seems to pick routes that I would normally choose (tested in the mountains). But here in south FL it does not do very much other than avoid interstates. I do not use the bluetooth features or do I listen to the GPS so I have no comments about them, but there is an audio out jack on the unit.
I hope my 390 lasts as long or longer than my old 550. If it does I'll consider it worth the price. If not, what choice did I really have?
I did buy a new TomTom Rider just before getting the 390. Used it on 1 ride and sent it back. I thought it was a major POS. The interface was hard to work with and it did not even want to follow a simple route that I created. Even at half the cost of the 390 it was $400 overpriced.