Awesome stuff guys, love your on point feedback. From what I've read it seems it's the one

not wanting to steer the boat again and I know this has been looked over but anyone rode the Spire back to back with the Megatower?
I have owned both and ridden both extensively. I sold the Spire and currently have the MT2 and prefer it for a few reasons that may or may not apply to you.
1. Stack size: I am tall - 6'2". The stack on the Spire is really low. I know this is like, a "thing" with Transition, and also Knolly, but it doesn't work for me. I finally fixed it with a new CSU and a whole stack o'spacers, but I don't think Transition wants you to do that - they certainly cut the steerer from the factory on the fork so that you can't. I think they want you to be bent forward riding it, I just didn't love that.
2. Sizing: The wheelbase of the XL Spire is huge - 1322mm. I would have preferred the geometry of the L, but then with Transitions insistence on the super low stack, I would have been stuck with an even taller stack'o'spacers - probably beyond what is actually suggested by the manufacturer on most forks.
3. Geometry: The Spire is a touch more slacked out than I ended up wanting, and the flip chip just makes it even more slacked out. There are many downhill bikes that are more balanced than the Spire.
The Santa Cruz sizing, fit, and geometry works better for me, and it's honestly a great daily driver for me, though I have it built up fairly burly with a Super Gravity casing in the rear and a coil shock.
Your mileage may very much vary.