Maybe not Virtual, Bare metal yes. That is to obtain the max download of 76Mbps or greater.
Yes it is with some performance loss, it will max out the CPU at some point. I use it with Untangle in a VirtualBox installation but because Untangle is a little heavier it will max out at 50mbps down CPU wise.
In a Virtual environment it may not be powerful enough to get above this with a pfsense install even though it has less resource use. The only way to cure that is to do a bare metal install which it will be more than adequate. I have Bt Infinity but I don't torrent/download a lot. So because I want to use the Microserver to the full I sacrifice 25Mbps off the 76mbps to get Level 7 Unified Security with spyware, add removal etc.
I would try this method first with pfsense either in win2008 in a virtualbox install. Actually I do have a virtual setup with pfsense I might try later and get back to you with max throughput obtained. In ESXI it will have the same limitations being virtual. You will have to try this yourself takes only about 1/2hour to setup and try.
Just tried pfsense in Virtual Box under windows 2008 I was able to get max speed without cores maxed out. This is with snort, squid everything on the http x 6 result is probably tainted because of this. There isn't much more headroom maybe OK up to 100Mbps. I still prefer Untangle but really these are two different things ones really a dedicated router/Firewall the other a UTM.
Here is the speed result of pfsense in the virtual.
Actually as a dedicated router I would long term take this route. Perfect hardware, but I wouldn't want the extra nic card and would go with the Akasa Euler Case