[MENTION=212762]Seattle[/MENTION] David: What is your reason for switching? I'm in the same process and have secured Silver now with BA and will obtain Gold soon. I buy premium fares only and therefore find BA a much better proposition, despite most flights on AA. Flagship access, cancelled my Admirals Club renewal as of next month, and have had a couple of great redemptions of Avios (one over 11¢ per Avios). What are you looking to redeem with Avios? Depends on your flying habits, for sure.
I've only used both beneifts twice for Admirals Club access. My BA Blue (once) and BA Bronze (once) did not grant lounge access with my ticket, but I presented my Admirals Club card and obtained lounge access without issue. That's certainly not the same as benefiting from BA status on an AA ticket, but it's certainly a data point.
[MENTION=9540]Dave Noble[/MENTION]: Grass is greener for me, 100%. I'd love to know OP's grander plan as far as travel for benefits. With UA*G per his handle, sounds like having multiple high-status alliance benefits is his thing. It's very situational, but Tier Point levels are reduced this year and will yield better expectations.
This is a great thread, will be monitoring for sure.