Does OS really fit "from birth to potty"?

So I ordered from my favorite cloth diaper site, Kissed by the Moon. Like I tend to do, I ordered Mystery Fluff. What's mystery fluff you ask? *Gasps* Only the greatest thing IN. THE. WORLD. Okay okay, the shock has worn off. Mystery fluff is a little bit like fluff Christmas. (with about 25% off retail prices!!) As in, you don't know what you're getting, but you know it's good! You can even make your list out and send it to Santa (Aka Tami). :) So head over there & check it out! ... Now that you're back, I'll continue. I ended up ordering Loved Fluff (Gently loved diapers) & Accessories fluff (no diapers, just fluff accessories!) & in my Loved Fluff, I got my FIRST bitti tutto! I love it. But it tempted me to try out all my one size diapers to see if they TRULY are going to fit my little monkey from birth to potty as they claim. So I nominated my slender, 40 lbs, 4 year old to model a couple of my various brands of OS diapers & here are the results!

This is a One Size Bumgenius in Mirror. Rise is kinda small but it fits. I think it qualifies to extend to potty training.

Probaby the best fitting. THiRSTiES Duo Diaper Size 2. It really fit him well.

OS Happy Heineys Aplix. He still had room in this!

The bitti tutto is not pictured bc he said it was hurting his hips. It also left red marks on his inner thighs. Now, I know most kids being potty trained are not going to be 4 years old & 40lbs, but he's all I had to test on! My winner out of the ones I tried (HH, BG, THiRSTiES, and itti bitti) would have to be the Happy Heiney's with Thirsties coming in a VERY close second.

What's your favorite OS birth to potty diaper? What has worked or is working for you? What has or didn't work? Leave me a comment!