Geedub..........I've gone all through the same decision / selection processes last year when I bought my first tractor (JD990). You're doing the right research; asking questions; etc.... and believe me - YOU are the only one who is going to own this tractor - not anyone else on TBN....get what you really want and start using it.
My 2 cents: Drive, drive, drive.....go to dealers and try every model they'll let you on....new, used, doesnt matter. You just need to get some actual seat time to start understanding the small things that could really matter to you later. Some I drove had really nice setups and others had controls (loader joysticks) in very uncomfortable or awkward locations for me personally. I know you want HST for doing tight FEL work, but don't overlook all the other operating ergonomics at the sake of the transmission selection. Shifting and clutch work for me is second nature, all the other controls were learned and having to stand up, reach over your head, turn around sideways, etc... just to find or use controls (FEL; PTO; MFWD; etc) is really going to ruin the experience - even if you have HST. Again DRIVE; DRIVE; DRIVE
My second 2 cents: If you are not really into doing all the maintenance and repairs yourself, you need to shop the dealerships around you for support services as much as for the tractors themselves. Great local support can really change the whole joy aspect of tractor ownership (unless you are into wrenching; welding; fabs). Walk out in their service bays; talk to technicians; "interview" the dealer personnel. These folks are going to be your best friends (other than TBN) if you choose to buy a used tractor - or even new.
Good luck