I have an amp with Steve now getting modded. I have several of his modified amps... Including monoblock conversion, balanced inputs, etc.
One of mine is a Rev A Platinum, but he really doesn't categorize mods like that anymore. It's more customized per person instead of a blanket list per category.
In fact, the amp he has now is one that I had him mod a couple years ago that was even more advanced than my Rev A Platinum. Things have changed so much in a couple years that he is adding some stuff and a totally new mod he is trying on my amp.
The reason I highly endorse his products is not only related to his great customer service and performance, but selfishly you save tons of money. You literally never have to pay dealer markup again. I originally bought my first DNA .5 over 20 years ago and it's still in service and always remains state-of-the-art and practically brand new with these mods.
At current day dealer retail pricing, I have close to a $20k amp (assuming just reasonable markup) at a fraction of the cost. With crazy markup you see in other brands, it's an even bigger bargain.
For example, if you really want a pure silver transformer like the ones Audio Note charges $100k, I know he's done them on monoblocks at a fraction of that cost (still pricey though).
People are starting to catch on though. I used to see stock dna.5 amps go for $400-500. Now they are actually increasing in price. I guess demand has picked up for these quality stock amps that can be modded to world class.
The only drawback I can mention (actually a positive depending on your perspective) is that he's got quite backlog of work, so expect to wait about a month or two for mods to be done.