Thought I was reading a Texas football forum for a sec.
@foxbat makes some good points.
If you stay with the all-in format, I don't know what the diff would be, aside from not having big schools play small schools, except maybe old conference rivalries could go away. 6A in IN might have difficulty finding a large enough mix of schools to change scheduling without some really long drives to opponents.
In TX, you have non-district (first part of season) where you can play whoever you want and results don't count towards playoff seeding. Some look at it as a long "pre-season". In district play all teams are the same classification. We always tried to schedule a few larger schools or opponents we knew would give us a tough game (referred to as "toughening them up for district") and a few we thought we could handle to let the 2nd string get some meaningful experience. Again, there's a lot of schools - all sizes - in TX to choose from, and used to making long commutes semi-regularly (1 hour +).
Also, with less schools to pick from it might be more of an issue, but districts in TX are re-aligned every two years. Some teams will stay in your district, and some new will come in, or you'll move to a different one - depends on how you look at it. So you're not playing the same teams year after year, but could be different in IN.
The one thing it would reduce, as mentioned before, are the small school vs. large school games. I personally don't get that whole thing after living in TX for almost 20 years. Maybe it's the larger number of schools, football culture, whatever, but you would never have a 2A playing a 5A here. A semi-final 2A team would get smoked by an average 5A team, if for no other reason than attrition. 2A probably half to 2/3 of the guys play both ways where the 5A has 2-platoon and plenty of subs. My kids school (large 2A) never played anyone larger than a small (4A) team in non-district a couple times who was known to be a below average program. We did play above average 3A when we could.
Apologies if this sounds like I'm rambling, but I am. Time constrained to post this, and lots of thought all at once.