The newer versions from Prefix-Arrow Racing should have added bracing on the block. In the middle of the 4 engine mounting points on the side of the block there should be a huge "X".
Also above the cam tunnel there will be additional reinforcement ribbing. Here is a pic of the block that I have:
The newest versions will have the ribbing seen here:
I don't have the newest aluminum block but one from 2014 and have never had any problems or leaks and has been run on the road course plenty of times. If there were actual problems with it then it would have shown up there.
I do need to get a second alum block for my next build though!