For 30 cal precision I use a TBAC 30P1 and an AWC Thundertrap. Both are rock solid repeatable/consistent. DB reduction is comparable - difference in tone more than anything (at least to my ear). The Thundertrap is old-school stainless and weighs nearly twice as much as the 30P1. I can't comment on POI shift when going from can on to off. I can't remember the last time I shot one of my precision rifles minus the associated can.
I'm sure the 30PS is just as consistent/repeatable as the 30P1. You're going to get some extra DBs with the shorter can/lower volume though. Everything is a trade-off.
I haven't had the opportunity to try the Harvester, but for some reason I've convinced myself that it's not intended for prime-time heavy use... more of a lower price point can for recreational shooters and hunters. Could be way off on that. That's just my totally uneducated bias. In it's defense I'm seeing and hearing, first hand from my dealer, great reports on both repeat-ability and DB reduction.
That's my 02