alanback: I think the underlying theory is similar in both systems, but in practice they behave very differently. First of all the parameters in the USCF formulae are set up for chess and are not suitable for games like gammon where luck plays such an important role. Secondly the provisional formulae are designed to allow a relatively small number of new entrants to quickly reach their correct rating in a large established pool of players. When applied to a startup situation they just introduce a random element. Similarly the formulae for established players only work in a mature rating system. So even for chess, the rating distribtions here are nothing like those of the USCF itself. You only have to look at the number of players here who achieve the rating ceiling of 2700 to see this. At times it seems that ratings are just proportional to number of games played.

As you know in FIBS everyone starts at 1500 and have to work their way up (or down) the ratings over the course of at least 400 games. Because of this, nobody gets a high rating by luck. By the very nature of gammon, it is impossible to try and get to a realistic rating playing less games than this.

The USCF itself uses a different rating system for correspondence chess which I believe is a lot like the FIBS system. I think this would be the obvious one to use at a site like this for chess and the other games. Again probably without the provisional formulae.