First off, 6' 173# means you have room to grow. Eating more will allow you to stay novice longer. I am doing an advanced novice program right now that is very similar to your last program (you call it the hybrid) and I like it a lot. The only difference is my pulling schedule is rows-power clean-deadlift on M-W-F but that is not a very big difference. I also do the front squats for only 3x3, since doing front squats for more than 3 isn't very fun and when I was doing 5x3 they were bleeding over and negatively affecting Friday's workout a little. You are certainly on the right track, figure out what works for you and don't be afraid to eat a cheeseburger or three to get yourself a bit more bodyweight. I'm not in the "you need to weigh 200# to be an adult man" camp as much as some, but for those of us over 6', being under 200# is a little silly unless you have a really really good reason like another sport or job that requires you to be excessive skinny.