Did you open the box yet?
Here’s my thoughts on the 28 vs 30.
The 30 gives you the ability to dial in some unusual conditions like shallow basin fishing where you might want a wide cone angle and lower power in shallow water. Or maybe over a school of suspended crappies where you want to cancel out some of the fish out on the outer edges of the cone.
I think it’ll also give you some better refinement in super deep water like 100’+. It has an 18’ zoom in addition to only the 12’ and 6’ with the 28.
The only other benefit you get is that you can select any depth manually. A slight issue with the 28 is that you can only select manual depth up to 50’. Over that it must be in auto-depth mode. On superior mine has the issue of reading the surface clutter in 100’+ as bottom in the top 5’. It can be really frustrating that you can’t send the depth range manually.
Vexilar has told me they can program my unit to be fully manual which would disable the auto range for free. I’ve been meaning to do this but haven’t done it yet.