Blimey – stumbled on this thread having just returned from a week out there.
I'd agree with most of the sentiments here – we rode some of the best, most scenic, most technical and most enjoyable singletrack I've ever ridden. La Varda was just insane – you just can't describe the feeling of riding such technical trails within 6" of a massive drop. Grange Hill, The Lakes & others were possibly more enjoyable from a purely riding perspective but every trail we rode offered something amazing – as others, I'm already planning the next trip out there.
As for riding with/without guides, it's the same as riding anywhere. I think Les Arcs is a good example of an area where a decent guide can really open your eyes to the riding that's available. However, had we had guides on La Varda, it wouldn't have reduced the chances of us plummeting to our deaths – we just would have had more of an idea what to expect. As on any trail, ride within your abilities and walk what you're not confident of riding.
The "trail guide" is crap – the majority of way marked trails are fire roads connecting a few choice bits of singletrack (the bottom of Red 7 & Black 8 are 2 notable exceptions). We were lucky and found a lot of the trails using a GPS & maps but I'd definitely use a guide for at least part of the time next year.
One question though – all the talk of La Varda doesn't mention the fact the MTBs are NOT supposed to be there any more. We were stopped by several walkers pointing this out and we spotted several signs stating this on the way out of the area – has this changed recently or has this always been a "sneaky" trail. Personally, no matter how good a trail is, I'd rather not ride it if it jeopardises future riding in the area.