I think some question could be raised around the test subjects themselves.
I mean a non-gamer is likely to prefer the simpler OSRS because it is simpler and they do not understand more complex gaming systems.
Whilst an experienced gamer is likely to prefer the more complex game because they can actually understand it easier.
Not to mention the very small sample size, 6 people doesn't really give a real idea of any actual trends or overall studies - Especially when you consider they are HIS friends you expect them to have similar personality to him and thus would likely have similar opinions on a lot of issues which creates an obvious bias.
The fact they are older players trying something aimed at a younger audience the 'retro' thing that reminds them of their childhood obviously has a bias (I mean ask any 20 something and they will gladly spout out about the awesomeness of rewatching kids shows from their youth despite the fact they look absolutely rubbish compared to modern things - its a natural age bias. Heck one guy even went on and on about liking it because it is retro.)
Some of the smaller nuances it brings up is certainly worthy of note though (even if we rather knew a lot of these already) - things like the new interfaces having no obvious X-button for logging out.
The fact that the darker more mysterious style is preferential to the bright-friendly style they plastered in to many newer things.
Tutorial isn't working quite right.
I find the 'approve-disapprove' scale a bit misleading on some answers though:
Graphics mostly people said they looked cartoonish and were alright yet they all got lumped in 'disapprove' despite the fact largely they didn't say anything overly negative.
Combat system again they mostly got 'disapprove' but that oversimplifies it because most didn't say it was like totally bad they just said it was a bit slow - which to me is more of a middle ground.
And some of them don't really show much at all like 'would you keep playing?' - That's kinda entirely subjective since for the most part these are not people in the target market and openly not mmorpg-type gamers. They aren't really the type you'd expect to engage and play longterm.
I'd definitely agree with the sort of 'start with old combat' type curve - I'd said a fair while ago that really you should start with click and wait and then sort of lvl 20 or so start to bring in abilities and build it up like that.