Does anyone actually use Extended Magazines in crafting?

[Sykar]

A single one sure. Two or more? Be ready to press F9.

a Psi build shouldn't have any problems with any rathounds before opening up the world and meeting Ancient Rathounds.  Even then, as long as you have traps or good mobility you should still have no problems.  All you need is a flare and the normal&Alpha ones go running.  Grab/craft a molotov or two and make good use of the fences and the beginning rathounds are trivial; get to safety while they're scared, then take your time and shock them through closed fences.

You sound like you get hit a lot in combat.  If you're playing a psi build - even one with little investment in the psi skills - you don't need to.  I would encourage you to figure out how to get hit less.  Once you're only slipping up and taking one or two hits of any significance in the larger combats, you may appreciate the bonus health, situationally, from things like the belt, or pig leather attire.  At the very least, belt, food, and two pig leather pieces made enough difference for my psi character that Silent Isle was non-threatening on Dominating. It was very threatening without all that bonus health, and the belt was more than any other part.

I was aware and use all the tactis and tips you mentioned sans flares. Also I did not say that rathounds are a problem, only that even against them the HP belt won't save you if you get attacked by more than one. And yes, CC and mobility is the key. Not the vigorous belt.

Silent Isle is not really threatening, just obnoxious because Broderick tends to draw attention from the PSI beetles and gets wasted which in turn leaves you stranded there, forcing a reload.

[harperfan7]

Yes, extended mags should at least double the capacity.  They make pistol mags that hold 30 rounds (though they look pretty comical). 

I was thinking about this the other day, though; why not change the gun crafting feat to instead give another enhancement slot?  That seems way better to me than just giving a bonus to damage.

[Arclight]

I'd be happy using the silencer on the 9mm barrel builds, along with the 5mm.

[harperfan7]

Silent Isle is not really threatening, just obnoxious because Broderick tends to draw attention from the PSI beetles and gets wasted which in turn leaves you stranded there, forcing a reload.

The trick, I found, was to throw caltrops on that far left shore, so they won't wander up to it and trigger him.

[Fenix]

The trick is to eliminate fast first rathounds, then bugs to the left.