So guys what would you do, am sitting here looking at my camera stuff, and I really want to get in to the mirrorless world BUT

I have the canon 750D/T6i with a sigma art 50mm and I kinda want a telephoto lens to, so I have looked around, and I can find some pretty nice once for around the same price as the r10 with an adapter on the used market.

Or I can get the r10 with an adapter. Plus if I get the r10 I can save up for the RF 100-400 canon lens. Plus plus I can sell my 750D/T6 for little under half the price with a lens( not the sigma art) to my buddy. So the question is would you get the r10 with an adapter and explore the mirrorless world, or would you get a nice quality telephoto lens