I like the basic thrust of your system. I have played a couple of other games that do a similar thing. One of them, if I applied its method to your game, you’d just erase the checks that you converted into an increase. That game works by the GM telling the PCs what they can put their checks against though, based on using a stat or skill etc in a scenario. I do like the idea that a player can put the checks into anything though. That is rather thought provoking, and could take the game in lots of interesting directions.
Thanks for answering so promptly. I hope to find time to try this out sometime this year because it really is quite intriguing.