There is a nice stl to check for effector tilt here http://www.thingiverse.com/thing:1369444 clip it onto your effector and move the head around, its easy to see if there is tilt. You can use it in several orientations.
I've got a similar problem but fixing it is on hold as my magnets in my magnetic arms are not strong enough and they keep becoming detached, I am waiting until stronger magnets turn up. I have redesigned a fan shroud to position the IR sensor as close to the nozzle as I dare (which is quite close as I've got the E3D silicone cover), this reduces the magnitude of the nozzle-probe discrepancy.
Whilst I really like the IR sensor, having just moved it from my corexy, it does seem a little trickier on a delta machine where a small amount of mechanical error in the build and therefore tilt, is inevitable until we start building them using robots or on jigs to ensure 100% mechanical precision. Its hard not to conclude that if a totally reliable nozzle to bed contact probe were available it would be preferable. I've tried FSR's and they seem reasonable. I believe some promising work with piezo discs is being done.