I am against rating decay on all ratings. Simply because as you get at lower ratings, you have casual gamers that cant and they shouldnt be forced to play any ammount of games per week(or per month). Respect casual users or die is the rule on computer industry.
As far as higher ratings, then i guess its generally a good thing. It has more to do with keeping a clean top 1000 with as less names per person as possible than with fighting smufing. Even though this is a nice thing for the community, this doesnt solve the smurf problem. And you suggested it as an antismurf measure. If anything, this increases the smurfing problem(altough there arent any intermediate ppl over 1800 to fight those decayed 1800 rated experts right now on aom TT).
Also smurfing isnt a problem for me and it will never be on any game(but this is a personal preference). ES should give more motivation to the ppl for using 1 name(like getting ranks for having more games on 1 name).
So, rating decay as nothing to do with smurfs. Its just a way to keep a cleaner top 1000. And IMO shouldnt affect lower ratings cause this will hurt casual gamers a lot(and they will probably stop playing aom). Also as soon as intermediates start getting higher ratings(1800ish and experts 2000ish), this decay thing can become a problem for them.
Anyway aom TT ratings are still screwed up(they will get fixed as time passes by and ratings spread over a little more) so you cant reach into any conclusions.