I'd like to playtest. I'm right there with Resa, I got excited about the MLP game even though it was a joke. Generation 1 was my favorite show growing up, and I think the tone of the show influenced me a bit to become interested in RPGs. I think when most people think of My Little Pony they assume it's half an hour of giggling ponies braiding each other's hair, but in Generation 1 at least there was quite a bit of danger. Although I don't remember any combat to speak of, there were a lot of monsters and magic spells used to kidnap or otherwise harry the ponies.
I'm not really familiar with the more recent serieseses. I'm guessing that MLP Tales is the one where the ponies go to school and talk about relationships. Personally, I think this is a little vapid. MLP Generation 1 and Pretty Cure over in Japan are two franchises that proved an action-oriented show can appeal to girls and be wildly successful. While I think it would be too much for an armored pony and a lava monster to go toe to toe in turn based combat, I think that there should be a threat. I would suggest a nondirect combat system, like giving the lava monster a chance to move the pony away from her goal, then giving the pony a chance to push a rock into the lava and plug it up.
I also like the resource gathering idea. These kind of shows always featured macguffins like crystal hearts or sprites that needed to be discovered or saved from evil. Rather than using them to build a barn, which is not very exciting, you could possibly tie them to character progression. Typically when all the macguffins are found something unexpected and beneficial happens to the characters, so I think it would make for a much more organic system of "leveling up" than awarding and keeping track of points.
Another thing I'd like to suggest is a system for increasing others' chance to succeed when one character fails. A staple of the show is of the ponies finding the strength to succeed after one or more of them has suffered something unpleasant.
I wish I had the G1 episodes on DVD so I could offer more than just my fuzzy memory, but as far as playtesting, yes please!