I just got my HU switched out only too. Went with the Kenwood with built-in bluetooth and an AUX cable, best purchase for my S. I noticed a slight improvement in my speakers with the new HU, but nothing to brag about. Stock speakers aren't great so that's my next upgrade.

 

Does the bluetooth work well with the top down?

 

works good enough for me. I don't receive too many calls while I'm driving, but I don't drive top down much to be honest since I drive alot of freeway.

edit: I honestly think is where the mic is positioned. I have my mic by my rearview mirror and it's a great spot, though sometimes I wish I had it placed on the extra space on the steering wheel.

 

Blasphemy! You don't drive with the top down! Just kidding I'm thinking of a new head unit myself and was deciding between one with HD Radio or Bluetooth. Both are best of course, but it's cheaper to pick one or the other. I may just go with HD Radio though, since like you I don't get many calls on my phone.