I had a 2012 Flash Alloy 29 with Lefty for a couple of years. Excellent bike – I was using it for duty that it was not really intended for, which is why I got rid ultimately, but a really robust bike, efficient peddler and mile muncher. I loved the Lefty, very stiff. I would say that it is not an all rounder – it’s definitely more of an XC specialist. I was using it pretty harshly on some of the fast, rough natural trails around me and downhill centres trying to keep up with mates on much burlier full susses and HT’s. Having said that it took the abuse admirably but obviously wasn’t quite at home on that type of terrain. It will easily cope with the average trail centre, but definitely primarily an XC speed machine.
So depends on what you mean by all-rounder. If it is a case of ‘XC most of the time with the odd dalliance with the rougher stuff’, then it will be fine. It got me down some pretty gnarly trails. If the other way round then it might not be the best option for you.