Well, they are non-magnetic but for me thats a down-side. They are rust-proof so that is an upside but as previously mentioned not a tough as the black oxide screws. Again though, On that particular kit would would be strong enough cuz its not a hard core basher so in this case Id really just...
I would say that its definitely worth while to replace bushings with bearings but how much of a tear down that would be I can't say as I dont know how widespread the use of bushings is on that kit since I dont own it.
As for stainless screws, I dont personally like stainless steel on RCs. Its a...