Tired of getting griefed, got myself a zapping forcefield o-doom after testing in SP that it's impervious to items that can bypass edit protection.
Complete waste of time.
First time I return to find my forcefield house intact, but otherwise robbed (or destroyed. not sure) of the most valuable stuff. There's a nether portal in it now. Fortunately still have a contingency supply elsewhere, decide to setup where netherportals can't reach.
So I set up above the nether bedrock far in the nether-sky, where I'm pretty sure you can't get a netherportal if you tried. Rebuild using up my contingency reconstruction kit, and it's robbed/destroyed in the 8 hours I'm away again. No netherportal, but someone got in. "I'm an idiot", I realize, "They can glitch their way up like I did to get above nether bedrock, right into my base". Well, there went the last of everything.
Forcefield #1 was set up with collectors producing excess infinite lava cells for geothermal, and the nether-sky base was powered by an excess of wind generators. The forcefields never turned off, I made sure of that.
So yeah, lesson learned. Forcefields just make you a more obvious target, and are completely worthless for protective value. At least they themselves are impervious, even if the blocks inside can have edit protection bypassed with buggy tekkit items :/
IIRC, reading about recent MFFS updates, forcefields now damage things inside the shield, rather than just whatever touches it. Or at least that it had a re-write regarding field security. That new feature would be appreciated in tekkit, though I'm sure top tier armor might negate that and make forcefields worthless again.
edit: someone is going to say "personal safes", yeah yeah. EMC flowers don't produce anything in a safe, nor do machines process anything while in storage.