I have the utmost respect for both Glen and Ernesto. From what I have heard and seen, they are two of the elite class of their profession of pool table technicians. We should all be lucky if we have our tables graced by either of them.
I would not hesitate to have Ernesto do the rails on my Gold Crown, even after knowing of the alterations that are made to the sub-rail. That said, I would feel much better knowing in advance that this is the way it works, rather than having my stomach drop as part of my rail gets sliced off.

Of course, I can imagine asking him what is up with that, and based on his reputation of being such a gentleman, I believe he'd be patient with my ignorance and explain to me that all the Ernesto tables that I love had gone through the very same "right of passage". At that point I would say, aha! Carry on then, sir! Slice it off!
That said, if I knew in advance, I might ask him if he'd be willing to install K55 rubber on there without doing the subrail mods, especially if I had a very new table. I'm not sure if he is willing to do that by request or not.
I don't fault Ernesto for going about this in an unorthodox manner. In fact, he came up with a creative solution to a difficult problem. The problem being that pool went through this phase called, "available cushions suck ass". In other words, I have read that the Brunsick cushions back in the day were the very best when they were made in Chicago, USA, but at some point they started outsourcing them. When this happened, the recipe was botched resulting in cushions that went dead prematurely... crystalized, worthless.
Anyway, I imagine that in the days when Brunswick cushions were garbage, Ernesto discovered Artimus, K66, and said, if I can make this work, we have a shot at recushioning the best table in the world which was hands down the Gold Crown at that time. He made it work and was and is a hero for that. So, I would argue that Brunswick is actually to blame for any heat Ernesto has taken over his method.
Now-adays there are good cushions widely available in the K55 profile. Perhaps there were all along somewhere, but I'm pretty sure there was a large group of people who couldn't find them at the time, Ernesto included. So now the K55 are widely available, what should Ernesto do? I think he's just saying, why change what I know works, and what people want. I cannot fault him for that.
I also can't fault Glen, who is saying, you don't need to make these modifications to tables, which are very difficult to reverse later down the line. Dartman summarized this very well. So neither man is wrong really, and I hope there can be a meeting of the minds where both can understand each other.
I think Glen came out misinterpreted, people got defensive and then he got defensive in return. I've talked to Glen and he's a great guy. From what I've read, he is doing a lot in the industry to try to get things standardized, which will benefit everyone. There are a lot of guys who don't do things by the book, because I don't think there even IS a book. For Ernesto, this doesn't stop him from making a table that plays awesome, arguably perfect, but in a general sense, not all technicians will be able to pull that off... which is why it's good goal to have things become standardized in the future.
It would actually be cool if both Ernesto and Glen could try things the other guy's way, and to have some pros test out the tables. Not with a bunch of us AZ'ers breathing down their necks and judging them, but in some kind of a private venue, test lab type of situation. Diamond would be a great company to drive this as an R&D type of effort. I'm not trying to volunteer Diamond, nor would I expect them to have the resources available to fund this, but I'm just pondering as to what would be an ideal direction to go for the future of pool, if time and money weren't a consideration.
Perhaps there is an optimal cushion configuration that is yet to be discovered. Perhaps it is neiher the standard (K55) nor the Ernesto way (adapted K66), maybe it's something in between or something different altogether. In reality, without a table company driving it, table mechanics generally don't have the time to do this, I don't think, because they are just too busy and overworked, like Glen and Ernesto probably both are.
Anyway, sorry for the long post. These are my thoughts, and although not very well organized ,I just wanted to share them for whatever they're worth. I think it's easy for people to be misunderstood on a forum. I think both Ernesto and Glen are great technicians, two of the world's best, and they both seem like great guys who care about their customers. We should be lucky if all technicians take such pride in their work as these men do. I think Glen and Ernesto as well as Oscar are all assets to the game of pool.