Ok, I have my 765T now and I'm going to write up a follow up reply for not only this unit, but also the Sena SMH10 and their compatability with other bluetooth devices. This reply will be the full answer that I was looking for when researching these GPS units and the SMH10 that I could not find a definite answer on.
The 765T does have bluetooth but it is NOT the same as the Zumo's. You can pair your phone to 765T however, you cannot bluetooth your phone via the 765T to the Sena. You can bluetooth the 765T to the Sena, but only voice prompts and mp3's come across. The phone only works on the speaker and built in mic on the 765T.
This is the only downfall to the 765T that I can find, other than the Aquabox is HUGE. Compared to the 765T, you could fit 2, maybe 3 of them inside the medium/wide Aquabox. Once the padding and wiring is installed the space is definitely occupied, but when you look at an empty Aquabox vs the 765T it is a shock how big it is.
The Sena is what the rest of this post will be about. The pairing ability might not be what is advertised, or maybe it is and I didn't understand it enough till I tried it. With the Sena you can pair multiple devices of bluetooth, only if they are of a DIFFERENT type. Ok, so what this means to the average user like me. I have a Samsung Convoy phone, pretty much a piece of crap, I also have the 765T and an iPOD Touch Gen 4.
This is where the issue lies, or so I found out, maybe others were aware. The Sena will only recognize different bluetooth devices if they are of different type. My Samsung POS is a cell phone with a built in MP3 player. Its bluetooth capabilities are headset, hands free, and bluetooth stereo. Great right? Not necessarily. The 765T capabilites are headset as well as bluetooth stereo. Both of these pieces you cannot change the bluetooth designation, ie, I cannot turn off any one feature of bluetooth on either device. The Sena will only recognize and allow pairing of different types of bluetooths, ie, I cannot pair two devices that have bluetooth stereo to it. So, this means that I can either choose my phone or my GPS, but cannot have both. We'll revisit this issue later.
My 3rd component, iPod Touch Gen 4. This has all the bluetooth capabilites of the iPhone, so bluetooth headset, handsfree, and stereo. So again, I cannot pair it with my Sena if my GPS OR my cell phone is paired.
So basically what this left me was 3 units that I cannot use simultaniously with the Sena. Much different than what the description of the unit is.
What my work around has been is, I uploaded all my MP3's to the 765T(in all honesty, I knew the Ipod wouldn't work in conjunction with the 765T on the Sena, but it was still a dissappointment). This allows me to listen to MP3's via bluetooth via the 765T, iPod out of the picture, not worth a darn on the bike while the GPS is hooked up, but I still have the ability to listen to music. The other work around is I had another verizon POS cell phone laying around that only had bluetooth headset and hands free capability's on it, so I switched phones and now I can pair the cell phone to the Sena and the Sena to the 765T.
So, in the end, I have a $200 GPS set up that the bluetooth works "ok". If I had a zumo, the iPod would still be out of the picture, but atleast I could pair my phone to the GPS and have my phonebook, caller id, and phone functions on the GPS instead of handsfree on the Sena, and also, the zumo would have paired with my old phone, and I wouldn't have to be using my "older" phone. But, I still have the ability with my old phone to pair it to the Sena along with the GPS, and built in MP3 player in the GPS to the Sena but not with the seemlessness and functionality of the Zumo's.
So there it is in a very long nutshell, 765T vs Zumo vs Sena.
Hope this answers some questions for some, as I wasn't able to find definite answers in my research even after calling both Garmin and Sena.
If anything wasn't clear, feel free to ask.