No that wouldn’t work. You would always need the TomTom to be present and turned on in order to listen to music. Also the Siri button wouldn’t work. For me, controlling music, podcasts, radio, phone calls and messages via voice/Siri is a must in any future setup. I realise everyone has different needs so I’m not pouring cold water on the TomTom Rider 550. I’m just saying for me personally, the iPhone, SENA and TomTom Go app combo is the best solution so far.
I may try a Nav 6, I’ve nothing to loose.
I think I've sorted the Rider 550, iPhone Sena 20S issue. All now working ok. Tomtom support helped out. My Sena has two Bluetooth channels so you connect as follows:
1. Connect Sena to phone on normal BT channel
2. Then Rider 550 to phone
3. Then Sena BT channel 2 to the Rider 550
Sena manual had instructions on using channel 2 for GPS.
The confusion is that Tomtom say connect headset and phone to the Rider, not the phone and also don't mention channel 2.
Tomtom link below
https://en.discussions.tomtom.com/rider-51/rider-550-not-connect-sena-20s-and-iphone-1036323/index1.html#post1223184
Hope that helps