Cannot give a difinitive answer but have a Connects2 unit on my Jazz and still retain the USB port. The problem is that it is not particularly intuitive to answer a phone call and have, annoyingly, missed several incoming calls. The unit plugs in where the CD player normally does, so you lose the CD player (not that I use it as all my CDs are now on USB sticks.
Have a Parrot MKi9100 which I installed on our VW Golf (MK4) which is fantastic and it has an accessories lead incuded that has (amongst other connections) a USB port. I found it quite easy to fit once I found the correct fuse in the fuse box (on the end of the dash under a lid, so no crawling around, contorting myself to look up under the dash!).
Also bought a Parrot CK3100 for the Jazz but am still struggling to connect it - bought a Connects2 wiring harness specifically for the Jazz but it was faulty (now repaired) but it seems to have too many connector blocks and too little instructions so have given up on that for the time being.
Bury do quite a nice unit but I have no experience with this and therefore cannot say if fitting is easy or if you could retain the USB port.
Not sure if the Jazz USB port is a proper USB connection - think it is a half-way-house type of connector that does not do everything a normal one does. I'm sure there are people on here who will be able to explain the limitations better than I am able to.
I think it boils down to exactly why you want to retain the original USB port.