Just tested it (thx dis for setting your base as it was): the whole thing really went fast but i think you get a pre warning. The main problem here is not the forcefield but using a jetpack (powerarmor one in my case). Moving at 20+ blocks per second makes it really hard to react to anything
As far as i got it it went like this: i saw a strange bulk in the lava. Since dis already gave hints where his base is i assumed i found it, ofc.
So (using the jetpack) i flew over there to check it out. Then chat messages got crazy. I think i got some warning messages there and then my powerarmor was removed. Without armor i dropped into the lava below and died ofc.
For me it really looked like i was just moving too fast. I was already naked swimming in lava before i could react to anything. Checking chat messages i saw a whole lot of warnings/messages . I think i got some pre warnings, too but sadly crashed at that moment so have no chatlog.
Fun fact: respawned at my base and noticed we did not place a single workbench there. And some places are only reachable with flying. Didn't realize i was already that dependant on powerarmor...
oh and thx dis for handing it back to me, didn't expect that.
Back to topic: i personally prefer to have the same set of rules for all servers. Just makes it easier. And FTB makes it really easy to get loads of resources anyways so you can easily remake everything.