OP – I know ‘grand day out’ well. Hardtail all the way IMO. Good tracks or tarmac pretty much. Nothing too rocky on it whatsoever, particularly if you ignore the little black diversion on the descent from Cam Fell (it’s not that good anyway). There’s a tiny bit of bumpy stuff on the run down from the Stake Allotments to Buckden, but they’ve laid a fair bit of material on it to ‘improve’ it so not much.
The only thing you’d fancy having a FS on is if you did it in reverse and wanted to blast down Dacre Lane next to Semer Water. That’s pretty rocky.
It’s a good route choice given the moistness.