Discussing the Right Tube Size for the Holy Trainer

I’m planning to buy a Holy Trainer v3 and would appreciate some advice on choosing between the small and nano tube sizes, based on what others have experienced. I have two devices that serve as my reference points: a CB6000s and a 2” custom JB from JB. The CB6000s feels about half an inch too long for me, while the JB fits just right (I might be able to go shorter with it, but I don’t think it’s necessary). Given this background, could anyone offer practical thoughts on which Holy Trainer size would suit me best? On paper, the small looks like a good match, but I recall reading that it feels quite similar to the CB6000s, which I already know is too large.

After accidentally dropping my nano device a few times, I’ve decided that the huge gap at the bottom is too wide for comfortable long-term wear.