Im holidaying in Aber this week and rode at NYA earlier.
I rode the Summit trail with Hippity hop loop from the Pendam trail thrown in - that pretty much covers all the single track. It's a really nice trail, some good shape to it and a fair bit of variety. The visitor centre is one of the best in Wales - the cafe is superb, much better than CYB and the Bacud nature trail and play park are great for the kids and their mum while you're out. Mrs Stoner then went for a run on the walking trails and enjoyed it a lot.
The summit trail is billed as 1.5-2.5 hrs which is a bit generous as I went round in 1hr + 15mins for the Hippity hop loop. But it is 100% singlespeedable. The Syfydrin Trail is pretty much the same as the Summit but throws in a big outback loop too which would make for a more substantial day out. Mask of Zorro is excellent fun, but the leg burner on the way back up is not so much
Id definitely go to NYA as a destination again.
Having ridden Climacx yesterday, Im not sure Id say the same about that one. It's OK but billed as 2-4hrs you can get round in about 1hr15mins and although there's nothing "wrong" about it, there's not much to attract you to it either. The final descent is OK, but not enough on its own.
Mach 3 was a good "out there" ride. Supposedly 3-3.5hrs it took me 3hrs on the SS and that's with a bit of navigational faffing. But it's 100% rideable on the SS and has some great open views - some grassy field climbs were a drag even in short summer grass - shouldn't want to do them in the rain and winter