Birdlocked discussion

I’m considering placing an order for a Birdlocked contraption once my paycheck arrives next week, and I could use some assistance with the measurements. Measuring the base ring is straightforward for me; the site explains that part quite clearly.

My main dilemma is choosing between the standard model and the new maxi version. As someone on the larger side, a CB-2k simply won’t work for my frame. However, I tend to be more of a grower than a shower, meaning I can shrink down significantly at times—particularly when it’s chilly out. Does anyone have advice on how to make this choice?