A lot has been said on these (especially by me) before, searching for "ashdown" in thread titles only produced these threads of particular relevence:
Ashdown Pedals Ashdown pedals price drop
I've owned all of them except the chorus:
Drive: Love it, and as many high-priced OD pedals as I stack agaist it, it defeats them all handily. I think it's worth the $100 I paid for it and much much mroe. YMMV.
Comp: I have no need for a comp, and I barely used this at all before selling it. The guy I sold it to (a friend), says it doesn't work well as a limiter, but then, hey, it's not a limiter, is it? Bought it for $70, sold it for $35, and felt slightly ripped off.
Filter: I really like this one. It's so tweakable, sounds synthy in a good way, and responds well to input dynamics. Also the output volume control is a very valuable tool for filters. It's about to leave my board once I get my MAM Warp 9 all set up, but I'll keep it around. Worth much more to me than the $50 I paid.
Sub-Oct: Love/Hate. Tracking is awful (worse than OC-2), tone is amazing (better than OC-2 IMO). I replaced it on my pedalboard with an Octabass, but when I'm recording I still use this guy for his filthy tone. The reason is that you have to play absolutely perfect and monophonic or the Ashdown will glitch all over the place, but the Octabass is much more forgiving. When your'e recording and you can afford to go back and do it enough times to get a good take, then it's worth using the Ashdown for the tone. Live, not so much. Well worth the $50 I paid.