Poor connection with Bluetooth headset

[punky]

I've just bought a Plantronics BackBeat 903+ bluetooth headset for my Desire. The connection is terrible though, especially on the street. At home under perfect conditions it seems OK but If I'm lying down and wearing clothes with it in my pocket, it keeps cutting in and out.

Is it normally that bad? Or do I have a faulty headset? Is there any way to improve it?

 

[Fishyweb]

I've found that my Bluetooth connections become unreliable if I have Wifi enabled at the same time. Anyone else noticed that?

 

[Usta]

Probably it depends on both - the mix of the phone + headset.
I've got a stereo BT headset (Sitecom), which I use to listen to music and make calls. While the connection is not automatic (probably, because I also have other BT device profiles saved in Desire), the call and audio quality is very good.