Having used Std., then 4S & now PW3, if I was rebuiding my motor now, I would put a 4S back in it. May be just my personal opinion, but it just felt more smoth & powerful to me right through the rev range.
Like Flo I have a PW3 but on a 750 and with a ported head and 9.7 compression it pulls OK but doesn't have the drive of a 2S for example. Carb needles now in highest position but I think a session on a Dyno would help. It pulls well from 3000, not much worse than std but for all the extra lift it is disappointing at 4500 + where I expected more go, though I have to say my bike is geared up a little via the belt drive at 4.114:1 overall. Depends what riding you want to do. It also makes for a very noisy exhaust, at least on mine it is noticeably louder than with std cam. I'd say if you want a nice rideable Commando stay with the std cam, the 850 is after all very torquey compared to a 750.
i've got a belt drive, 23 tooth drive sprocket, single mikuni carb, ride on all roads from motorway to country lanes and the standard cam has served me well for the 3500 miles i've done since having her on the road. was looking to see if there was a general consensus on an overall best option. sounds like everyone likes something different which is great.