Like others have said, there may be local code issues that require the use of conduit in low voltage installations. Beyond that conduit makes cable install easier and faster. It also makes re-fit easy and fast, sometimes without it re-fit is impossible. Consider that AVL install usually comes in last. If there's conduit in place (and properly installed/not blocked) they pull in lines quickly and easily and then spend their time terminating. Without it they either have to come before walls get drywall or they have to get lifts in and do a much harder and more time consuming pull. If it's a free air pull at the end the presence of lifts/scaff etc will slow down other trades from finishing their work or if those trades are done it will make the AVL process even harder.
My money would be that if you had the AVL install speced out running in free air the difference will be more than 64K due to increased labor costs. If cable is installed before walls go up and the drywall hanger puts a screw through a cable bundle that's gonna be another expensive, time consuming, and dirty fix too.
You may need to have a talk with your AVL contractor about ways to reduce the conduit needs. Crosstalk though, that's pretty much bunk unless you've got a long run closely in parallel with mains cable.
If the bids are already in, and if the bolded statement is true-shouldn't the cost of conduit be on the AV installer? I mean, they can either invest labor for cable install, or they can do conduit if they feel it is "best practice"? Or perhaps the difference should have been listed as an option?
If there really is that much trade off, then one shouldn't have to pay the AV installer for the extra labor for a free air install AND pay an EC to install conduit?
