I'm on Entyvio but I still take my probiotic everyday. I use Align. Yes, I think they are crazy expensive too, but I use it as an extra tool to help me in the fight against pouchitis. My budget doesn't allow for VSL#3 and I can't get my insurance to pay for it, so that remains out of the question for me.
Can I prove it works? No, but I figure it can't hurt either.
Just a thought!