Just to chime in on these ...
1. It might be a better idea to level out the power curve past 20th level, instead of having it skyrocket to infinity and beyond, as per the ELH.
In my experience, the actual skyrocketing happened during the range from 15th-25th level, maybe even to 30th.
Once the characters get up above 30th-35th level, it is pretty flat using the ELH rules, and it's actually not much different than the below "gain a feat every ___ XP." Especially if characters stick with a single class. And if they don't (i.e. they do the Master of Many Prestige Classes thing), they tend to have lots of abilities but those abilities don't have a lot of staying power.
I noticed this because of one of my few houserules. In order to keep players from feeling ridiculously helpless, I'd instituted a "bootstrap" eearly in the campaign. If you missed games here or there and ended up behind by more than the bootstrap levels, you were automatically leveled up to the minimum.
At low levels, this had to be close. If you're 7th level and adventuring with 12th level characters, that's a pretty dangerous endeavor, and if you're 12th level and hanging out with 17th level characters, it's even worse due to how much power ramps up from 10th to 20th level.
On the other hand, these days I've got it at 15 levels. Being a 45th-level character in a party where there's 60th-level characters is nowhere near as deadly - the party has many resources for dealing with threats; typically so long as they survive for a round or two, they can counter anything other than an encounter specifically designed to be a TPK.
2. While I agree that you need to include lots of support such ad DM advice, epic monsters, epic feats, etc...the actual mechanical rules themselves could be pretty damn simple, such as my "gain a feat every ___ XP."
Perhaps. And I agree that simpler is better. Last thing I want is for the epic rules to be another 500+ page tome. However, I'm pretty darn certain that there's more to epic play than a new level advancement chart.
If nothing else, feats appropriate to epic levels are crucial, and something needs to be done about magic. Even something as simple as "all absolutes go away above level 20" is huge (antimagic field and freedom of movement, I'm looking at you).
Core Pathfinder is conceptually pretty simple, so long as you ignore all those messy classes and feats and spells and creatures. It's kind of the same thing. Compare the SORD to the Core Rulebook and you'll see what I mean.