My N4 revamped, re-plated Slim gets used for about 25% of my shaves, generally 1 week per month. If I include the shipping & insurance from USA to UK, it's possibly the most expensive razor in my den, as I wanted the N4 specifically and waited for one to be sourced for me, then reconditioned and plated. I decided to go for the traditional finish, although Rhodium would have been nice too.
My problem is that I also love the Tech and I bought a lot more of those, so feel I have to rotate the different ones in!
I found the Fatboy I borrowed a little too 'fat' for certain areas. I suppose that's why Gillette brought out the Slim!
For me, it's a #6, #4, #4 for a 3-pass and if I'm in a rush #7, #5 for a 2-pass. I haven't been disappointed yet.
I do get a bit more satisfaction if I use a NOS blade, such as the Gillette Super Stainless, Patinum, or Scottish Perma-Sharp's, but I'll save them for something a bit more 'special', as I haven't got many.
I find the Gillette Perma-Sharp's are a perfect match for me.
I assume everyone else has their own favourite blade to use in their Slim?