Running Asterisk under Hyper-V

Firstly I know that running Asterisk under any VM is a bad idea and dedicated server is by far the best option. But I have two customers that are running Windows server 2008 and they had a wish to have Asterisk installed under Hyper-V.

The installation went rather smoothly (after installing Linux Service Integration Component everything was in order) and the first tests were looking promising.

Both Hyper-V servers have very low load (very close to 0, more or less they only run Asterisk VM’s and file sharing) and the Asterisk VM’s have only a few phones connected to it (pure SIP system, enabling only SIP calls). Interesting thing is that both customers are reporting random choppy sound on phone calls. The choppy sound happens very randomly - not dependent if it is internal or external call. Since only these two customers are reporting these problems, I got to suspecting Hyper-V.

Does anyone have any experience with running Asterisk under Hyper-V?

Would it be better that I use another virtualization tool (VMware, VirtualBox)?

Are there any tweaks in dahdi_dummy that can help improoving Asterisk timing sensibility?

If I search google for this, I get very different opinions from professionals. One are saying that running Asterisk under Hyper-V has no problems, one complain only about choppy sounds only when playing system files. So I am hoping that one of the forum members has some advice on running Asterisk as a VM.