Mirrorless bodies definitely offer some advantages. Personally, I like the information available in the EVF, and more importantly the full-time DoF preview in the viewfinder.

For lenses, I’d say only update if needed especially if cost is an issue. The RF 24-105/4 is a good lens, but the adapted EF version you have would also work. Optically they’re pretty similar, the RF lens does have the control ring (a nice feature once you get used to using it), but you can get the adapter with that feature so you have it on all EF lenses). That’s the only lens priced the same as its EF predecessor. The other RF lenses cost more but add more (e.g., the 100-500 has an extra 100mm, the 70-200/2.8 is much smaller/lighter and optically better, the 24-70/2.8 adds IS, etc.).

By all accounts the R5 is excellent. I’m certainly happy with the R3 as a replacement for my 1D X, and the R8 is also great as a travel camera, FF sensor and a lot of performance for the cost.