You can go the Sears route (I did), or the Seekonk route (which I also did). The Sears wrench in in/lb will come in handier for other tasks than seating a SCAR barrel. The Seekonk wrench is...well, just for the SCAR, as far as I'm concerned.
One thing going for the Seekonk wrench is that it is an offical part of the SCAR kit as issued...so, there's only the pouch (which you can't buy, period) and everything else left to collect, if that's your cup of tea
To be honest other than trying to fix barrel canting issues (which I did with mine), there's pretty much no reason you'd ever need to remove the SCAR barrel....unless FN starts selling SCAR barrels in their CQB and long formats. So, either way, it's not really "needed"....