If you like your Canon, why not keep it, and simply get a macro lens. That is what I would do.
While I am a Nikon guy, I am not a fanatic. There is NOTHING wrong with Canon.
Jumping ship to another brand/format is a major decision. I would only do it if, there was a major issue with the camera that I have, or I NEED something that only another brand can give me.
In my case, I switched to Olympus, simply to reduce the weight and bulk of my kit. As I get older and my injuries act up, the weight of my Nikon kit was getting harder and harder to handle.
Sometimes it is simply emotional. If you LIKE Nikon enough to make the jump, go for it. But you should really think through the emotional reason.
Example I may like Canon or Sony, but neither will give me anything that I don't already have or can have with Nikon. So why change?
Be cautious of the "grass is greener on the other side of the fence."
It isn't always greener. IOW, you may loose something that you take for granted on your Canon. Examples:
- I have friends who have Sonys and they say the camera is great, but the UI stinks, compared to the cameras they had.
- For sports/action, the autofocus on non-pro level mirrorless cameras perform poorly compared to even entry level dSLRs.
- The new mirrorless cameras are nice, but the lenses are $$$$ EXPENSIVE, ouch.
As for focus stacking, that gets complicated. Either camera based as with the R5 that
@photoflyer uses, or VERY carefully done by manually turning the focus ring and using software to stack the images. I have not done stacking, yet, so my knowledge of stacking is minimal.