Wow, Ryan, that is fantastic. I commend your diligence!
As far as "excessive" growth...as you are a keeper of colubrids and a generally knowledgeable herpetology student, I'm sure that you're aware of the debate concerning captive reptile growth. To the best of my knowledge, they've never definitively been able to pin negative consequences to excessive growth when all of the other parameters are met. Meaning, as long as the animal is healthy both in appearance and behavior, fast growth rates in and of themselves haven't proven to be a problem. I still remember when keepers and herpetologists became livid that people were raising Retics and Burms to breeding size in a year. As far as I know, they haven't linked any negative effects to this practice (aside from all of the unwanted pets).
The problem seems to arise when the fast growth is a symptom of a dietary flaw and a larger problem. I watched a local herp keeper ignore the dietary recommendations of myself and others in the care of his hatchling Three-toed box turtles. At two years of age, on a diet of earthworms and trout chow, the turtles were nearly 5 inches in length. Unfortunately, they were horribly deformed (in my opinion anyway). The whole time, he just kept saying, "But they're eating it all and growing so fast, they must be healthy." I think that this is one reason why "fast" growth has such a negative stigma. It can actually be a side effect of improper care.
Steph said something very wise a few weeks back..."...it's not the quantity of growth, it's the quality of growth." I'd say that about nails it, and it goes for "fast" or "slow" growth in my opinion. Your hatchlings are showing nice, clean, even, tight, smooth, "proportional" growth. If it seems faster than others, I wouldn't be too concerned until a red flag pops up.
In addition, my experience has shown me that some populations of box turtles grow faster than others. For whatever reason, the NJ box turtle that I used to keep grew much faster than the Southeastern US box turtles that I currently have.
In addition to chubby legs, bulging eyes can be a sign of obesity (especially in juveniles) due to the presence of a fat pad behind the eyes.
Ryan, have you added vegetation to the diet regimen at this point?
