The biggest negative in my opinion is that except for the mount, it locks you in to ZWO's products. I've just started using a mini pc and NINA, which at least to me for astrophotography is more versatile but more complex, and not really useful for EAA as far as I can tell. Edited...
If your focus is WAY off, you may see nothing that you'd recognize. You can change your time to, say, 5 seconds, and click the "loop" option and adjust the focuser while NINA is taking image after image. Also make sure you picked the correct camera when connecting. Not sure if you...
but I will tell you why I usually avoid them, particularly on the end of long refractor draw tubes where you may have to adjust your 2" diagonal orientation or while switching out 1.25" eyepieces using a 2" to 1.25" click-lock adapter. ...
Your link to the Barlow you have on order does not work so I can't see what product you are referring to. A back focus of 54mm for a Barlow does not seem right though. "Back focus" means that you need to move the focuser farther into the optical tube... so backing away from you...