After having used all 3, the Itworks std, pro, and lulzbot aerostruder extruder for awhile now, I can say conclusively that the itworks pro is probably the best of the bundle.
For flexibles, I found I needed to bump temps up a good bit on the itworks3d pro partly because of the A2 nozzle being less thermally conductive than brass. On an older 1.75mm standard one I needed to put in a slightly longer ptfe tube by the nozzle, e3d datasheets now call for the addition of a nylon washer to bridge the same distance gap on old units. New one was fine with the flush ptfe as expected. Without the ptfe I experienced jamming on high temp materials (CF-PC running at 280c) and id expect so with flexibles as well unless you bump the temps up further. The itworks variants were lighter. The pro has a nice led on it and a gap in the front which makes it much easier to clean the nozzle. Keep the fan speeds low. Even with the latest firmware a 100% fan will shut down your machine on all 3 versions. The PID and heater just cant keep up. Outside of bridging, I max out at 40% on any material. The 2.85mm version can handle flexibles a bit faster, but there is better material availability with the 1.75mm.
Watch out if you try to use the full build plate. I had the coolers on these crash into the raised plastic of the wiper pads and foul things out a couple times. Been pushing those parts over to the CR10S5 or Formbot Trex2+ lately.