Well, perhaps trying to compare relative worths of victories is not neccesary. Afterall the object is to win, regardless of game type no? And why is a win under one type of system any better than a win under another. You can't say one win is easier than another, because it's then easier for the other players in that game too, and they still got beat.
So perhaps merely tracking wins and losses as far as your rating goes is sufficent. But it would also be good to keep a brief desription of the game settings for each posted game resolution. Then if you were considering playing someone, you could see how they have fared in the particular type of game you are considering. But that would be just for informational purposes, not any sort of rating.
When enough information is accumulated, you could have seperate Ratings I suppose based on game type. You would have one overall rating that encompased all your wins and losses, and then seperate Ratings for games of each type. If you have no games of a particular type, then you simply would not be rated in that Category.
Geoschmo