I've owned them both, and they are each great amps. But there are some differences.
The 5153 50w has a decent clean, and the crunch goes up to very distorted. About the only sound I couldn't get out of it was a great classic rock crunch. The high gain channel is very heavy and gets nice and thick. Prolly too thick for use with a band, but it sounds VERY nice at home, and will give you endless hours of tone smiles. But the volume jump between clean and crunch make it unusable for me as a gigging amp. But that's just a gigging issue.
The Diavlo has great cleans, a nice (very usable) crunch channel, and the onboard boost takes it into that distinctive Fortin modern high gain. There's just nothing else like it. You can set the channel levels at unity gain, so it works great for a gigging amp. The gainiest settings aren't super thick like the 5153, but they are huge and still cut through. It offers a bigger range of usable tones than the EVH, and if you happen to love that great Fortin kerang, there's nowhere else to get it.