Hi. Probably the general complaint about Fast Tracks is, apart from the initial cost if you really only want or need 3-8 of the turnouts, is the lack of detail. The skeleton of each turnout is the PCB ties, which understandably won't have tie plate details. Even then, the rather convenient flex-ties that each package contains, which are laser cut thin plywood, and very good, do not have any real detail.
I have built a number of the standard Code 100 #8 turnouts for HO, as well as two #6 double-slips. They are very good, very slick very reliable, and generally look and function very well trainwise. Someone who wants more details would be better off with commercial or with Central Valley.
If you are not currently proficient at making handlaid turnouts, and would like to be, the Fast Tracks system will teach you how to make what you need, even custom ones that are unique. However, Kalmbach will have pdf articles by authors who tell you how to make turnouts from scratch for much less.