I still own a canon system. I have used Sony, Fuji, and Olympus/Panasonic. I ended up with Olympus taking over as my main system. I wanted Fuji to work very much. I still carry a bayer sensor x100 everywhere. I just couldn't live with the xtrans. I love the Fuji primes.
If you do try a smaller system, there is some adjustment. I find if you do use out of system lenses, make sure you use a speed booster from metabones. Quality will suffer other wise. At least in my experience. It also starts feeling silly to use large slr lenses on such small bodies. A lot of people are using the canon shift lenses on mirror less because there aren't any other practical solutions for perspective control yet. I've gotten excellent results with the 17mm tse. The 70-200 also gives excellent results adapted. The same system lens from Olympus focuses faster, is better quality still, and doesn't need an adapter. I have all the canon glass, but I still end up using the dedicated system lenses.
I also find that I should till need the same discipline if I expect the same results. Sturdy & quality tripod, timer, optimal exposure, etc... Smaller cameras don't mean we can be slack on our skills unfortunately.
Depending on the kind of images you make, you will be surprised how far mirrorless systems have come. The new e-m1 mk2 at 20mp really makes the fight pretty even between it and 24mp DSLRs. I don't look at the high ISO area because I rarely make critical work at high ISO. And when I do, there is not a camera out there whose ISO 3200 or 6400 isn't good enough any more.
The high resolution cameras are great, but I find their benefit only useful in scenarios where I need that feature as a tool. Otherwise the extra work to obtain perfect results and the extra file size can become a burden. For me an hdr multirow pano from a 5dr would be quite a bit larger that it would have from a 16mp mirrorless. Printed size is still limited to my wall space so the higher res benefit is lost. Guess which files I prefer. The benefits I do get from the smaller cameras is higher than the benefits I receive from a little extra resolution and file size. Same reason my medium format gear stays home unless a client is paying for it. It's nice, but I can get the same and better results with a lot less work on a smaller system. And I can get shots I just can't get with larger equipment.
I highly recommend renting a system who's lenses appeal to you and give it try for a week or two. Handling and approach will be different from the canons. Especially with information in the evf about exposure. Seeing a final image live is nice.