It is always good advice to follow the manufacturers recommendation.
Alaska also sells the SWG power vent in a kit (see the link below).
This link is broken, either the page no longer exists or there is some other issue like a typo.
The disadvantage to the Tjerland Direct Vent unit that mounts on the stove is that the pipe inside your home is pressurized with CO. Any leaks result in gas in the home. The benefit of the SWG type unit is that the pipe in the house has a draft and will not leak unless you somehow lose power (and even then it will be small amount for a short period of time) or do not set the unit up correctly using a manometer....
So in the final analysis make a choice based on what your needs and budget dictates and by all means talk to an Alaska dealer. You can pay $600 for their kit or buy the same parts yourself for a significant savings.