We struggled with code reviews, the bids diff tool caused crashes so we couldn't even use that. Merges were a huge pain, our packages at the time were too big but I've heard the gripe around the net a bit too. Then there's that PITA SCD task that looses all config each time it's opened. Believe there is at least 1 commercial equivalent for that one. Maybe 1 that pushes more of the work to the database would be good.

Reliability would be the big consideration for moving from ssis to a 3rd party product as main editor, support for future versions etc

BIML looked very interesting and seemed to be getting a lot of traction as well.

I'm mostly out of data work now, but id be curious to hear what your thinking of doing here?