May I inquire why you are wanting them over reference PCB cards? The reference board performs the same as the FTW at this point, so you'll basically be paying for the RGB feature. The FTW is still less costly than founder edition, so it isn't a bad price, and I am jot trying to sway your decision at all.

The Classy may be bound by the same "rules" as the FTW and all other cards. At this time, it is very hard to speculate as many people with the ability to conduct extreme overclocks are having issues pushing these cards very far. I would honestly go for the FTW or Classy just for the RGB feature in mind, and the slightly lower cost, and keep in mind that voltage hasn't helped even people using Liquid Nitrogen all that much at this point. K|ngp|n and very few others have made it past 2300 mhz with crazy amounts of voltage. So far, K|ngp|n has been able to edge past 2800, but they butchered the board and soldered new parts on to get to that number.

Go in with an open mind that the extra voltage may not actually help. Also, you said EKWB. If you aren't prepared to take the cooler apart and risk a charge for removing parts of the cooler, you may lose the RGB feature completely. The waterblocks typically don't come with lights, and if they do, usually they are single color and you have to pay extra. I know some RGB let's are out there, but it may require modifying some other parts to get them to fit. Just keep all of this in mind.

If they have very low profile, mini 4 pin connectors, RGB is 100% possible. You may have to "work" to get them running. :-) I spent hours running a dremel on my waterblocks to make the connector fit, and it was beautiful once it was complete.

Just pressure test the Waterblock ahead of time. You don't have to do anything to the gpu itself.. Also, I used a terrible dremel. I want to make things impressive, and those waterblocks with RGB are impressive.