There IS a way to get this idea out of your brain: listen to Nightcrawler, get the gun, and satisfy the craving. Start with the G29 carry gun. I prefer full sized guns for almost every purpose, but you like smaller ones for carry, so get what you know. The G29 SF is roughly equivalent in size to the G23. The weight and bulk should be similar enough that you don't notice the difference. What you get is a couple hundred more foot pounds of energy, dramatically increased penetration, and longer range.
As I said, you don't give up the .40. Hang onto it. Bulk practice, backup gun, teaching shooting classes. .40 ammo is way cheaper than 10mm. In any case, after you WECSOG-ed the s___ out of the grip like that, you're probably not going to be able to sell it anyway. So hang onto it.
I believe, however, that after you got it, shot it, and loved it, the G29 Ogre Edition would be your new everyday carry, and you'd love it forever. Get the G20 later. It'd make a good truck gun, open carry gun, hunting companion.
Hell, here's an idea for the G20: tritium or fiber optic front and adjustable rear sight. A 10mm with a 6" barrel has some range. Zero it for 25 yards or so. Get some Double Tap and/or Buffalo Bore loads for serious business and use the .40 for plinking. It'll give you a gun with all of the capabilities of Larry Correia's STI Super Gun at about half the cost.
Best of all? You're packing your own brand. Nothing says "I believe in Crusader" like carrying a Crusader.