^ Paul’s about right, I’d ride from the door on closer stuff though both of Jon’s routes can be linked to from Allendale if conditions are decent and you have the time. If you do the first of Jon’s, the top bit had a massive heather burn going on across the track at the end of the last dry spell which may affect things (but doubtful). Otherwise a few bits can get a bit damaged if there’s too much traffic in wet spells (has become vastly more popular in last few years – much more than more local to Allendale tracks), but most is fine if you’re sensible. As Paul says, there has been some “upgrading” on ROW closer to Allendale which might make some of them a bit more all season, luckily the best bits of singletrack are/were still hanging on recently.
RE conditions, I usually avoid the best singletrack in wet spells, but until this last week things have been unusually OK since about April last year (!), so if it’s relatively dry for the next couple of weeks all should be good. XC hardtail (geared or singlespeed) my preference most of the time. If anything like the last week/weekend, bring the road/gravel bike or a boat instead (excellent road tiding in all directions, on just about any road). Enjoy!