Definitely demo one.
I have a 2012 medium ASR5c with 120mm Reba 20mm fork and Kashima CTD shock. I demo'd an alloy ASR5 in Glentress (along with an alloy SC Blur) before I bought mine. Personally, I didn't get on with the SC. For me, this was replacing my HT so I wanted something stiff but with some cushion.
I've also demo'd in the past an alloy Zesty, elsewhere in Scotland, and I found that to be a good bike.
I'd say that the Zesty and ASR5c are not poles apart from each other in feel; the Zesty is definitely more plush though.
I agree with bigjim above about 5-10psi making a noticeable difference to pedal bob. Get it wrong and it'll feel crap but get it right and it's very good IMO.
Best of luck. I hope this helps.