I saw the stake tool when ordering from Brownells.
It looks like the way to go cause it allows a direct downward blow on the stake, rather than a punch being at a bit of an angle.
and would seem to be more fool proof
That's the only caveat, getting the correct angle to get to it properly. That and getting the tip sized. You are pobably better off getting that one, but it's not a big jump to machining the slide for a dovetail sight. If you plan on doing more though the tool would be a good investment.
If you stop and think about it, using a center punch to stake the sight would drive the excess metal to one side of the sight's tenon. When you go to grind down the excess for clearance you'll end up with a tenon that is only staked on 1/2 of it's circumference or half way round.
I could possibly shoot loose!
I think you're wise to consider getting the staking tool. Good call.