By all means cut the brown portion of the top of the raja if you feel it has rooted in properly. It looks from the base that its ready to pop. I've done this 4 or 5 times now with plants that were stubborn about coming out and the results were outstanding.....100% so far. I had one Burmese blue that I didn't do this to because I was new to this last year and it never did pop out of the top. It did put out a nice pup though and grew from that.
As usual if you're tired of looking at Pisang Ambon, you know where to send it
( a man can dream!)
Thanks for the update, keep them coming.