I need to replace a standard toilet and am interested in using a wax free toilet seal. The Fernco brand looks like a good choice. Are there any reasons why a wax free seal should not perform as good as a traditional wax ring? It sure would be less messy, more forgiving and easy to install. I don't mind the price difference.

If you don't mind the price difference then feel free to use one. It should perform every bit as good as a wax seal. When you're setting over 100 toilets a year then the price comes into play.

Totally agree with cost issue if installing a lot of toilets but I only need to do 1 or maybe 2. The positive reviews on line outnumber the negative. The only issue of concern is the adhesive failing eventually.

I have used the Fernco and the adhesive will not fail. It is best used on a new toilet but can be used on an old one with extra care to remove all the wax, outside solvent to clean off residual wax, and then solvent clean it again. I have used hair dryer to heat the horn of the stool before applying the adhesive. The adhesive is so strong that the plastic remains when removing the toilet even multiple times.
Advantages: never leak between toilet and flange
Disadvantage: maybe hard to fully push the waxless down into the flange. There are a three sizes Make sure you get the right size: see the below link. Cost maybe $4 bucks I will never use wax again unless forced to.
There are other waxless seals however this is the only one that glues to horn of the stool. I think the other waxless seals are inferior to Fernco.

[www.fernco.com]

I've read a lot of reviews. Several complain the adhesive failed sooner or later. But with any glue or adhesive assembly if mating parts are not properly prepared the joint will fail. Lots of glued together airplane parts flying around out there so i know there are some good adhesives available.

Would it be of any benefit to apply a bead of silicone around the seal on the bowl?