HTv4 Small or Nano size?

I've been experimenting with chastity for a couple years now. First I self-locked in my own CB-6000s knockoff from Amazon, and then I was locked by a key holder for a while in an authentic CB.

Since being in quarantine, I decided to lock up again in my old CB knockoff, but it's not always the most comfortable or well-fitting cage for me. I decided I want to invest in a better-fitting and higher quality cage to self-lock in and decided on the Holy Trainer v4.

The CB6ks is a bit more than 1/2" too long for me. My head basically occupies only about 1/2 of the space in the head of the CB6ks, which I've always found to be rather dramatic and oversized relative to the overall proportions of the device. My flaccid penis is about 1.75" measured on the underside, but I don't think this measurement is 100% accurate, as my scrotum is pretty high and tight.

I read that the HT Small tube is a bit smaller than the CB6ks tube, and appears to have a less dramatic head, so I decided to order it. However, I'm having second thoughts upon more reading of posts of people moving from the CB6ks to the HT. Some go for small, and some go for nano. It seems like since the snuggest possible fit is best, I should go for nano. Since it seems like HT is operating slower than usual anyway, I think with an email I would be able to change my order. Should I?

I am also worried about the reported design flaw with the nano: the open underside. Yet, from the pictures on the HT site, it looks like this has been resolved and the bottom has been extended in the newest version. Can anyone confirm this?

 

Thanks for the comparison pics! I checked your Twitter, and it looks like you fill up the CB a little more than I do, and that you fit into the HT small, nano, and nub all quite well. Which one of those fits you the best for longer-term wear?

I want to make sure my cage is comfortable enough to wear all day and all night, and with enough room to make it easy to put back on after cleaning, but snug enough to prevent all erections, which the CB doesn’t do for me.

And thanks for the clarification on the design. That makes me a little more confident in thinking I should go for the nano, but I’d like a little more confirmation in terms of size first.