For the small boost of fps over the 1080ti and LOSS on some games that aren't SLI optimized, it's not really worth the pain in my opinion. The 1080ti can give you almost 40% the performance boost without any pain.
Unless I'd find the same GPU as yours, on a huge sale, I'd probably not do it. Either exchange it for a 1080ti non-reference card, or wait for 2080 (then prices drop and you can SLI cheap or upgrade if it's a lot better) but in my experience, the 980ti was almost 10% slower than the 1080 so it wasn't worth the upgrade since I could OC.