The standared Blazer set-up is whatever the customer wants. You can run either a 20" or 25" shaft on the 2220 Fisherman or the 2220 Professional. We sell them both ways.
We usually recommend that if you are not interested in going super shallow and typically do not attempt to run in water less than 2 feet that you run the 25" shaft. If you like shallow water mostly then you should run the 20" shaft.
The only problem with the 20" is that there are conditions where you can experiance some cavitation issues.
To me, the best set-up for every day use is the 25" with a 10" Bob's hyd. jack plate. You mount the engine all the way up on the plate so you can either run shallow or drop the plate down for heavy seas.