Auto to manual conversion. If you could do it over....regrets, pitfalls, long term opinions???

I know this has been discussed many times before but I'm hoping to hear some feedback from you guys who have already done a swap...or who have experience with someone else's swap.

Which transmission did you switch to? Are you happy with the decision? Did it change the character of the car? Did the performance/efficiency gains pan out? Would you have picked a different transmission if you could do it over?

I've been daydreaming again and looking at some of the complete conversion kits out there. It looks like there are some choices these days varying from finding a parts car to complete kits...
Brewers offers a complete swap to an A833 4spd
Brewer's Performance - Mopar A833 4-Speed Transmission and Component Specialists

Silversport offers the option of a Tremec 5spd or 6spd with a hydraulic system.
Articles - TREMEC TKO, TREMEC Magnum & SST A41 Conversion Kits for 1964-1976 Dart, Valiant, Barracuda, Duster, Demon, & Scamp

Any warnings or serious omissions we could benefit from knowing about with these kits?

Any insight, feelings, opinions, information, horoscope predictions, etc are welcome!