Can't speak to the ALG personally, but I don't know why they changed the trigger at all. People seem to love the ALGs and I'd wager to guess they're better than the Enhanced FCG.
I've had a couple SAM7s with the standard Arsenal trigger and it was an amazing trigger. My SAM7 triggers broke at just over 4lb, and I had an SLR-101S (same gun as SAM7 before Arsenal changed the name) that had a 3.5lb factory trigger.
I got to handle the SF-84E and the trigger was considerably worse than the factory Arsenal trigger. Again... I am not sure why they decided to change it.