COnsidering getting rid of the ISS on my 700 mountain rifle and replacing it with a real firing pin assembly. WHo has replaced this thing and how was the outcome?

I have not replaced the F.P. assemblies on my two 700's. I know that many people consider this "ISS" a joke, or at least an inconvenience.... on that I cannot disagree. I simply don't use
the feature. As the bolt assembly is the same as any other 700 (except for the ISS feature)... unless, somehow, it malfunctions... I will simply leave it alone (and save the money that I would need to spend on replacement bolt assemblies). I can't prove it, but I doubt that this gizmo will ever cause any problems. As a matter of fact, I actually ground down one of the "keys" that came with (one of) my 700's... and made a neat little sight adjustment tool.
If you truly desire to replace the assembly, Brownell's has the non-ISS firing pin assemblies for $65.00.

Well the firing pin spring sure looks different and when i lift the bolt handle it sounds like a squeaky hinge or the spring on a garage door just not so loud.

For me if i ever own a 700 with a ISS replacing that anti gun extremist pacifier will be quick speedy. as a matter of fact i have bid on a few on e bay just in case i find one at a good price.
remingtons making a 700 bdl in 270 wsm that i would really like to have and you can rest assured if i do that plastic tit will be gone!

Oh its an abomination thats for sure