Never had any lbx or lbt kit, but do own some condor kit, & like you I served, back when the issue was '58 pattern, & to be fair almost any manufacturers kit is more than up to the job when it comes to airsoft, so the choice should be what you like the look of & more importantly what fits & is comfortable.
I, like many, have been sucked in to the mindset of "REALLY NEEDING" certain kit, only to find it was overkill on so many levels, & not suitable for my genuine needs.
I'd say get a minimalist bit of load carrying kit, as an example I sometimes run a Molle bandoleer, fitted with 4 TT 7.62 shingles (also take 5.56 mags easy), an inverted serpa which makes for super quick draw, & still have room for a bottle pouch & a coupleof pistol mag pouches, couldn't be any easier when it comes to running & gunning, at least til you've established your playing style & needs.
i have other rigs set up for long (48hr) type milsims etc, but for regular gamedays less really is more.
Mark