Success rate? Its hunting... There is no way to know if a mature bull will be close enough to the strip for a guy to shoot, the weather isn't 60 degrees and sunny, etc. Once the rut kicks off there is no way of knowing where a bull will wander to. All those guys in the business put guys where others have had good luck before, or in areas where moose tend to travel through. There are so many variables to contend with on a 7-10 hunt that if one messes you up, you'll be out half your trip (fog/wind/rain for instance).
Also keep in mind the requirements for a legal bull. Some areas may not have more than 1-2 legal bulls available for harvest. Generally a group of 2 guys will kill at least one moose, sometimes two. The problem is once you get one on the ground you lose hunting days hauling/dealing with meat. Say you are on a 8 day trip, you killed a bull on day 4, and it took you 2 days to get it back to the strip. Do you really have enough time to kill another one and get it back? At some point you have to call it... That's the reality of flyout hunts, logistics never stop. I always plan on 2-3 extra days on the back end for weather, or killing an animal right at the end of the hunt.
While being in shape and competent is certainly an asset, you also have to have luck on your side. If a guy is willing to pack a moose 2-3 miles, you'd have an extremely good chance of killing a moose. You may want to ask yourself if you want to pack one that far. Its 6 really heavy loads (500+/-lbs of meat) plus a rack and cape, which could be a load each. No trails, and potentially chitty ground conditions. Every area is different.
Renfro has a great reputation as well, but is similar to Papa Bear, really expensive. But they also fly out quite a ways and its more expensive to operate off the road system. I don't think Papa Bear and Renfro is really too overpriced, but they are making a decent profit, because... well supply and demand. I won't pay those prices, because its still just a moose hunt and they can be had much closer for less.
There are lots of transporters that don't really have to market or are internet savoy. Word of mouth books their fall up. You can get in on a moose hunt for under $3500 in lots of places.