I thought the limit on YC was you -- that the partners didn't have enough attention to distribute to any more startups (or more tablespace to sit them all at for weekly dinners :)
How are you planning to expand sideways without drastically reducing your (non-monetary) contribution? Wouldn't this just make YC less valuable on it's own merits? You'd retain the brand value, but that would diminish pretty quickly if the startups you funded started getting crappier. If you did diminish your responsibilities, and the startup quality didn't go down, what would that say about the value of your higher-bandwidth contributions before?