I revisited this today after reading your post. I made a new table looking at HPS for the basic SH rotation to see if such things happen. I have previously calculated the stat values but I kept the total values within achievable ranges. I went over the top a bit to see if I could find funky scaling.
Basically intellect gains stat value as we stack it, but slowly. To make Intellect 2x better than mastery (so making it the gem of choice) you would have to add 17k intellect, or 107 int gems. Ain't gonna happen. Eternal flame scales similarly in that int will gradually be worth more over other stats but not in the achievable range. There is more to the post and what I did and why here.
There are lots of ways to judge a player's skill and they are all not perfect. Progression? Sure, people can be carried, or they raid a ton. Item Level? Lucky Drops, 25man loot train. Logs? Play with poor raid aware team members, non healing/absorb main tanks, no Disc Priest in raid, cheese parses. Taking anyone piece to judge the validity of ones argument is a flaw, but people also need a way to filter out the good and bad. Progression is one of the easiest ways to do this and I challenge you to find a 10 man holy pally who is 14/14 heroic spec'ed EF spaming LoD. Thok on up the fights get much harder and there is no room for carries in 10 at that point (but Ilvl is certainly helping).
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I would argue going UBER mastery would be better with a Disc Priest because they are already shielding the incoming damage. Fight fire with fire, shields vs shields. It is already hard to get raw healing in with shields. So the best way to combat more wasted heals is more shields. Thus Shields > All. Those are my 2 cents on that. Unless of course you think your Divine Light direct heal will beat your Disc Priests atonement smart heal to your intended target!!