Hey Slip,
You are definitely a savvy angler...and yes square is better, offers more room all around with little waste in the inner compartment. You actually get more than 20% more space with square and we have gone square
The inner diameter is also critical for larger plugs and it was a major consideration, they will be 2 1/4 inches wide on the inside (which fits even the widest plug you can realistically use)...the large bag will have 10 of these tubes and small plug bag will have 3 as well as an area in the front of the bag for bucktails & tins....
As for us selling them at the shows, we do not sell direct so it is very important to get the word out to your favorite retailer to contact us so that we can make arrangements with them to stock their booths for the shows and then their stores for those who may not be able to make it to the shows.
Thanks,
Kadir