(I actually left in 2014 but that wasn't an option.) Anyway, the primary reason I left was due to Express Scripts implementing their corporate nonsense with a non-compete contract required for senior PMs and above. I had many lengthy discussions with HR and senior management, including president of the company. He did go out of his way to call me on 3 occasions to discuss my concerns and really try to talk it through. I was very impressed by that, but it was just not an option for me to put my salary at risk for a year.
Even though Express Scripts acquired UBC a few years ago, there are still many changes being made at UBC.
UBC hasn't totally implemented electronic TMF, so they do have a lot of paper TMFs, which isn't necessarily a bad thing - again not a fun of a system that doesn't function the way it's supposed to anyway - or claims to be "efficient" but it is so far from being "efficient" it's laughable. So, the fact that UBC doesn't have a full eTMF wasn't a huge con for me but I know others have different opinions in this area.
Another con from this Express Scripts merger (or whatever you want to call it) is the loss of some vacation days. From what I understand UBC lost 2-3 vacation days because they were required to now follow the vacation days that Express scripts has. I didn't experience this myself as I started and left in 2014 but I understand others were upset about this.