iPhone 4 + JVC KD-AVX77 and Motorola H710

Anyone else with an iPhone 4 also have a JVC KD-AVX77 car head unit and / or a Motorola H710 bluetooth headset?

I'm having issues with these devices all paired up via bluetooth.

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With my JVC KD-AVX77, when I pair my iPhone 4 with this head unit both the Hands-Free Profile (HFP) and Advanced Audio Distribution Profile (A2DP) connect automatically.

The problem with this is that when both HFP and A2DP are connected, when I receive calls and answer them through the KD-AVX77 I cannot hear the caller and I'm not sure if they can hear me. To get calls to work properly, I have to go into the KD-AVX77's menus and manually disconnect the A2DP connection with the iPhone 4.

This issue only occurs when the KD-AVX77 is paired with my iPhone 4. With my Blackberry and HTC Touch Pro. 2 I don't have these issues when they're paired with my KD-AVX77. ALSO, with both the Blackberry and HTC Touch Pro. 2, I can choose in their menus which of the bluetooth profiles (that they support) I want to pair with the KD-AVX77. So I can choose to pair both their HFP and A2DP profiles or one of them.

I cannot find this option in the iPhone 4 (to choose which bluetooth profile or service I want to pair).

Another issue that occurs ONLY with the iPhone 4 is that I cannot sync its contacts list / phonebook with the KD-AVX77.
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With the Motorola H710, when I answer a call the call audio always stays on the iPhone 4 even though both are paired and the H710 is on. To get the call through the headset, I have to tap on "audio sources" then on "Motorola H710". With both my Blackberry and HTC Touch Pro. 2, if the Motorola H710 is powered on and paired with either and I get a call the audio goes straight to the Motorola H710.
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Anyone else experiencing the same or similar issues with the iPhone 4 with JVC KD-AVX77 and / or the iPhone 4 with Motorola H710

Or

with the iPhone 4 and similar devices (car head units and bluetooth headsets)?