I think this is a good idea. It gives more time for the game to be exposed to a wider audience, which is a good thing IMO. You may want to mention in the early access blurb that you've been doing early access before it was invented on Steam, and that you've got a perfect track record of finishing your games.
In general, I would recommend to move to Steam distribution almost exclusively, perhaps just adding GOG as a DRM-free alternative. You don't need the management overhead of running things separately from Steam. Every sale you make that's not on Steam gives you a little more money, but it's more important to get the Steam numbers up.