Just picked up my X from the stealer today; they actually put in a rebuilt tranny

but he said "all the internal parts are new" and "the work and the new tranny is guaranteed for an additional 2 years, regardless of when my CPO warranty expires (which is next year)".
Car definitely shifts better, more aggressive, and the stealer did a complimentary detail for me. Hey, it's something right?
Anyways, I was wondering if it would be worth it in the long run to hold onto my X (2001 4.4i) and purchase an aftermarket/extended warranty or dump it and get a 4.6/4.8? Suggestions are appreciated!