The front diff mount is solid anyway with the bushed located in the main cross brace. As things are now solid at the rear these would have even less stress on them with majority of the twisting now transferred straight to the diff cradle.
Only benefits in terms of performance with no real downside except perhaps some additonal road noise but with any type of larger exhaust it's not something you really notice.
the biggest plus is cost though....$10 of alloy and 10 minutes with a hand drill and vice