Looking to get some longer travel forks for my old old Sub5. 80mm SID SLs on now with hope mono M4. IIRC the bike can only take up to 125mm travel, beyond which I guess it gets a bit chopper-like & slack in the steering.

Thinking of RS Revelations stopped down to 120-125mm. But forks these days seem to have post mounts. That makes it look like I'll have to get a new front brake too

Help.
1. what fork options should I also consider in the £250-£400 range
2. if I need a post mount front brake, what's going to be similar in heat capacity and stopping control to the mono M4 with 180mm rotor I now have?

a) you could also check out RS Rebas with Maxle.
b) back up a little. Is there a post mount adapter for your brake of choice? I'd be surprised if there isn't…

Good call on the adapter. I'd had a look around but you made me look closer at the Hope website. There are a few adapters but the most appropriate looking one needs a 20mm bigger disc. 200mm disc sounds scarily big. Still, £40 (rotor + mount adapter) sounds less than a new brake.

I want to stick out for QR this time as rehubbing my wheels doesn't appeal.

Could always get some older revs second hand? Cheaper and IS mount.