So.. I found this fascinating... because I have to agree with @Annaerith on this one. The majority of the "complaints" I've seen about PvP rewards were that they were a pittance compared to the time required to even be competitive. You can find above where, I think @HKdirewolf played over 28 hours and barely made top 100. Ridiculous. So yes, for 30+ hours of gameplay THOSE rewards should be scaled up, or be EPIC, to use @Sirrian's words.
HOWEVER, what more people have said (from my experience here on forums) is that they wished that the rewards AS IS, were just enlarged to allow more players to sit at the table. And that is was is being completely missed here in GW! Once again you create a new feature that rewards only 30 players (1 guild) out of a player base of 30k? (I wont pretend to know how many active players there are.)
And while the gems thing is an issue... I think we've forgotten something VERY important. The real "diamond" is the unique GW troop offered. Everybody failed to notice that the top spot is awarded 100 copies!
Which means that, ASSUMING GW Points will mirror PVP closely enough that the GW leaderboard will resemble the current Guild Rankings Leaderboard, Guild A, who is always on top of said Leaderboard will take first place 2 weeks in a row, securing 200 copies of said troop and immediately having it Mythic. In that same time, my guild which will fight its hardest and probably, based on current leaderboards, place in the 15-30 range, will secure only 40-48 copies of the same card.
I think the real issue is the DISPARITY of distribution between Rank 1 and Rank 50, which when you look back and realize there are literally 100s of Guilds behind that just makes you hear that, 8-bit sad music "WAH WAH WAH". And none of us VOCAL, GoW supporters want to see the devs work this hard on a feature that is going to hit the game as a disappointment to the vast majority of the SILENT player base.
I think its safe to say that most of the people "complaining" stand to do fairly well within the given structure, assuming we understand it correctly, our concern truly is for the good of the game.
Lastly, but not least, the people that want or need the EPIC rewards @Sirrian are not the people getting them under the current design, based on our expectation of how the leaderboard will play out. You should be making mid level guilds feel like they have a shot at EPIC rewards as well. And 400 gems to them is epic, 1500 is a windfall, for sure, but to people that are sitting on 6k+ gems... The EPIC is lost before it begins.
Sorry for the wall of text, but its all from a place of love and passion for GoW!!
tl;dr- Rewards need to feel EPIC for everybody to fully engage, or entice, the ENTIRE player base into participating in GW.