In reply to TobyA:
Interesting topic - I have been giving it a lot of thought recently. I have both classic Quarks and Ergos. I don't have trigger loops, just a clipper leash on the RHS on the classics.
I find that climbing stuff that I am comfortable in, with some less steep patches, snow to clear etc, that the classics are better. However, when it comes to the vertical, sustained stuff and beyond (5+/6) the Ergos come into their own. As has been said, it's not the climbing that is the difficult bit - it's hanging around placing screws (blunt ones usually!) I find it's much quicker, less tiring and you can shake out if you want.
I think there is a subtle physiological diffrence in the two types of axe. I have done a lot of training with both types recently and really tried to understand what part of your body is being used in each case. The classics tend to use forearm and lats much more - the Ergos more the bicep. This would explain why non-rock climber types coming from other sports (like me for example) find the Ergos easier to use. We tend to have more developed arms, esp. biceps, that are really not that useful in rock climbing.
If Joe average tries to do pull-ups, he'll usually be able to do more palms facing than palms away - because it uses a more worked and stronger muscle - the biceps. This may not be the same for most climbers, because we all tend to train pull-ups , palms away as its much more sport specific. Maybe you should try doing some pull-ups, palms facing and a few biceps curls in the gym?
I now find that I have no mental comfort from having leashes - to start with I felt more secure but that has changed in a short space of time. I find the Ergos handle much easier to hold for a longer period of time. The only place I don't like them is when space is quite constricted and you have to make a short swing to get a placement - then I find the angle of swing difficult and go often take a few goes to get a "stick".