I think there are too many variables to say that one or the other won't work. IMHO, getting six stakes pounded into mountain soil trouble free on the first try is just dumb luck. As far as bending them, I'll chalk a lot of damage up to user error and who is wielding the rock or chunk of wood, the accuracy of the strike, and having a feel for when you have hit a rock under the surface. You can bend any stake if you run into a rock and just keep pounding.
I would put my money on the tougher alloy in general. I still have some titanium stakes in my collection, but the Groundhogs are a good balance of cost/weight/strength/holding power and my first choice. My real misgiving with the ti wire stakes isn't so much with getting them pounded in, but having them *stay* there. My guesstimation is that surface area counts for holding power.
I got some DAC "Vee" stakes with a tarp I bought the other day and they look good. I noticed that they are the same stake that Hilleberg packages with their lighter tents. The ones I have are 6-3/8"(16cm) and 0.45oz/12.9g, 7075-T6 alloy. I've seen them marketed by Kelty, Eureka, North Face and others in both 6.25" and 7" lengths. Big Anges calls them a "j stake" http://www.bigagnes.com/Products/Detail/Accessory/J-StakeReplacementStake