Intes Alter 603/MK66 v. NeXstar 5i

I have a very well collimated Nexstar 5i. I know that this Celestron 5 inch OTA is a proven winner. My main interests are planets, messier objects & double stars. I was debating whether or not I should purchase a 6 inch Russian Mak. Either the Intes Alter 603 or an MK66. Would changing to a Mak design and adding an inch in aperture over my N5 give me a noticeable improvement in visual observations? Or would they be more subtle? I have heard many great things about the Intes Maks and have read countless positive reviews on them. I was wondering if the change would be worth it. Or am I better off staying put and purchase a larger scope (down the road) in conjunction with my N5. Any input is always appreciated. Thanks, Luis.