My other concern is that your stated goal is to keep the gap between divisions from growing too large. In my opinion, this could exacerbate economic problems if non-monetary inflation occurs in the player transfer market.
Assume that you can easily divide players into "tiers" based on which league level they would be an average starter in. The top-most tier would be above average even in established D.Is, then you'd have D.I starters, then D.II starters, and so forth. Each tier would have an average price for players in that tier--for comparison sake, let's assume Tier 1 players average $5M transfer price, Tier 2 (D.I starters) $4M, Tier 3 $3M, Tier 4 $2M, and Tier 5 $1.5M, and so on. If general inflation of 50% occurs, we'd have new prices, such as Tier 1 for $7.5M, Tier 2 for $6M, Tier 3 for $4.5M, and so on. This has now RAISED the cost of replacing your starters as you promote, as the gap between tiers has grown by 50%. If the BB's operate under their mandate to allow promoted teams a reasonable chance to stay up, the expected response would be for them to increase the promotion bonus. This increase in bonuses then increases net operating revenue, which adds monetary inflation to the mix and begins to reinforce the inflationary cycle.
Economic damage could be done by the pendulum working the other way as well. Assume the BB's see the inflation in the transfer market and try to control it by reducing the money supply via the auto-tuning mechanisms. Depending on the way that information was dispersed to the players, this change may take a few weeks to "trickle down" to owners if owners don't realize immediately that their revenues are going to change (or have actually changed). The longer the delay is, the more likely that people will hoard money out of either fear or a need to fix the budget crisis created by the delay in owners figuring out the change in situation. This would then probably add a non-monetary deflationary pressure to the transfer market in addition to the monetary deflation, "whipsawing" the transfer market back the other way.
I'm sure that you'll do everything possible to prevent Armageddon, but I'm concerned that even a 2 season inflation followed by 2 seasons of correctionary deflation could be very detrimental to the BB economy. To that end, I would like to encourage some degree of increased transparency with respect to the macro numbers and how much the BB's are targeting transfer price inflation with their ongoing money policies. I think an arena maintenance cost might bear looking at too, in order to prevent a steady "preference shift" from arena investment to player investment, but that's the subject of another thread's debate.