Hi Alex,
I notice a bit of mirror flop on my old u-210, so added a FTF. A great addition, especially with a focus motor.
I occasionally use a dew shield when there's a lot of dew about - adds a bit of weight to front, but is counter-balanced by FTF.
As others have stated, primary mirror does attract dust, but can be blown off easily & gently washed occasionally.
The finder/carrier is awesome at both roles, but I also like to use a RDF. So I bought a slightly longer screw that attaches the primary cell to the tube, and thread it through a RDF base first and then back into the original hole - works fine. Alternatively, you can purchase a K-Astec adapter to piggyback RDF on the mewlon finder:
https://www.kyoei-osaka.jp/SHOP/k-astec-fb53.html
Also, I was uncomfortable with the two small screws that attach the Tak dovetail to the foot of the u-210, so I tapped a couple of extra holes in it and added a bigger dovetail bar. I've never heard of the original Tak screws failing, & the u-210 is light, but I feel better knowing the extra screws are there.