OK, just back from Mabie and Ae so here's my own take…
Ae is, as widely reported, not very good. There's fun in there but you really have to work hard for it, a lot of the sections feel like they should be about 10% steeper so you're pedalling the downhills like mad just to get the trail to work, and constantly losing speed to the incredibly lumpy surfacing. I don't see me going back tbh, if they could condense all the good bits into a 10km lap it'd be pretty nice but it's 26km, 1/3d fire road and 1/3rd pretty ropey "singletrack", some of which you could drive a car along. Shame. Still, there are bits that'll stay with me, there's a really beautiful flowing section through trees about halfway round and Granny Green Love has some really nice moments too. But too much is just hard slog and too much is slightly disappointing. Omega Man is mince frankly and the Shredder's hard work, you need to know the trail I think as it's poorly sighted, so you're charging up on something but you don't know what. But it strikes me as not worth learning/
Mabie… Ah, but it's lovely in places. Like an extension to Kirroughtree red, with dabs of Drumlanrig. One bit reminded me so much of Talnotry Hill, only easier. At its best it's really damn good. But other bits were a slog, again, and there were too many bits where there was a chicken run and a proper line and no way to know which one you're on til you're committed, that's annoying. Mainly though the problem is it seems in really bad shape. Fair play it was soaking wet today but half the trail was under water or plastered in organic mud, it seemed like they'd surfaced parts of the trail with cow shit instead of stone. I get the feeling it's had a real lack of resources since it was built? But even then, I'm not sure, some basic stuff like drainage just wasn't working. Loads of potential though, but it needs knocked into shape and it really needs more trail.
I really enjoyed Mabie though. Ae, not so much. Can't see any reason to ride there with the local competition. Wish I'd just done a second lap of Mabie or gone up to Drum.