Been researching the whole rSAP thing in a bid to get my company to get me an rSAP mobile, which would mean I could order the premium car kit and use it. The only other 2 models available to us seem to be the Samsung Galaxy S3 and the Nokia Lumia 920, but our IT tell me neither have rSAP capability (although apparently the S III can be just made to work with a frig, but it's flaky.)
This does beg the question, if Apple's main competitors in the Smartphone arena, have dropped rSAP compatibility from their latest phones (which is very surprising seeing as rSAP is a Nokia invention), then why are car manufacturers still producing car kits for this protocol, when it seems the mobile industry is moving away from it.
My worry would be with this trend, that in one or two years time, with updates to all the major phones, that no one will support rSAP, meaning that a £400 accessory becomes unusable, or you will forced to use an older phone, or a special one for car use only.
Please note, I'm not "into" mobiles so am only reporting what has been told to me or what I have found on the internet.