In my opinion, that really turns PoW into a "Pay-To-Win" game and that's gonna scare away many potential players once they realize, which is a pity.
Let's be realistic, very few players will accept to pay 689 $ a year just to have a chance to win in an internet game, even such a deep and addictive great game as PoW...
My suggestion is to make all achievement slots available for gold, that would encourage players to spend their gold wisely in game and fix instantly that "pay-to-Win" problem.
With all the recent changes, many new useful options have been introduced that can only be paid by trophees (memberships, auto-repair, auto-heal, auto-quests, etc...), so people will still have many incentives to buys trophees but those are confort features that doesn't give an unfair advantage in the game to the biggest spenders.
It's up to you, Nate and Eric, to decide if you want to give PoW a chance to become a popular game with a huge player base or to keep it a playground for a very small group of rich players who can afford to pay for all the boosts...