I can confirm (at least by playing campaign mode) that the no-mercy map now works and although there are a few glitches (guns at strange angles, clipping and sometimes the bots don't seem to know what to do) they don't cause any crash to desktop for me. I recommend downloading for L4D2.
The version myself and Kearney are working on is in some ways good and in others bad, I hope to wind up with something worthwhile though, it's getting there
Good points:
1) No need to mess around with your pak_ VPK files at all, the maps etc are all added into one VPK file that gets installed into your l4d2\addons folder
2) We have spawned new weapons, items, and on occasion new zombies such as the CEDA zombies/armoured police in place of the old stuff.
3) It has automatically added in new models for certain things, for example the minigun is the l4d2 version wherever it's used in the maps.
4) It's very dark, which is awesome imo, feels a bit darker than it was on L4D possibly due to the light differences in L4D1 and L4D2. However it's not too dark by any means really, feels atmospheric in my opinion

5) Removed med kit spawns from all maps I could find beyond the first ones. No defib spawns.
Bad Points:
1) Some of the events are a little sketchy:
a.) The intro on NM1 doesn't work at all, the helicopter flies etc but instead of the camera panning in at the start you start with a view at 90 degrees horizontal and then you "stand up" so you're facing level but the wrong way. Really odd

doesn't effect the map itself though after this.
b.) Many of the events seem to have a few less zombies than normal, for example at the lift on NM4 the zombies stop arriving when the lift is a few floors from arriving and i'm sure in L4D1 they kept coming until a little after the lift stops.
c.) I can't really get the event on NM5 to fire at all, I press the radio once and it
2) Some of the sound files etc are missing, so it doesn't play exactly the same as in L4D1.
3) The maps we used were the .vmf files from the L4D1 SDK for the No Mercy campaign. The biggest problem here is that these are Campaign version maps and as such are not designed for VS very well. Have had to add in infected ladders etc to places, mostly it's ok but NM5 the place you defend at the end is a pretty different layout between Campaign and VS modes.
I think right now the biggest problem is the events, namely the intro on L4D1 (i'd rather just skip the helicopter intro completely if I can't get it to work) and being able to start the event on NM5.
If anyone here is experienced in mapping events in L4D using Hammer perhaps they would be interested in helping us a little with this? I have only just started to use Hammer in the last week but have already learnt a lot, but I don't understand much about how the events fire yet!