To answer some of your questions.
The the body of a REO is nearly the same height as a standard Credit Card--save for the
juice well on top. It's almost 1/2 inch narrower than the CC. The Mini is pocket friendly, so if you want to carry it all day, you might consider it. The full specs are stickied on the REO forum with pics for size comparison.
I'm a bottom feeder person. I bought the Old Goat before I bought my REOs. I totally understand you wanting to try a different bottom feeder before you spend the money. The Old Goat did what I wanted it to do, which was let me know I liked bottom feeders. For the money it was fine. That being said, the REOs are a step above the Old Goat in every way. Mine leaked a bit, the plastic...was plastic. It showed wear quickly, but for the money it was fine.
I personally prefer the Grand. It gives me the option of
vaping all day with an 18650. The AW IMRs are now rated at 2000 mah, which will give you a very long, very consistent vape. I also use the "5 volt"--really 4.8 volt green batts --if I want a warmer vape. I can also stack batts to get to 6 volts, but I don't need 6 volts.
I went from attys, to Cisco spec attys at Avid, to Boge 2 ohm cartos. I still use the cartos, but I'm a convert to the Avid HH357 atty--best atty I have ever used. I also like the ikenvape iO6, but prefer the HH357.
There is certainly something to be said for controlling or even just regulating voltage on a VV device. That's what a VV tube mod will give you. The downside is you are either going to be refilling cartos or getting into tanks.
The REO is a self-contained unit. You have everything you need contained in the PV. It's tough, completely mechanical. You can wash it out, dry it off and keep
vaping. It will bounce off concrete, with only a battle scar to show for the experience.
I think you are doing well to weigh your options. There isn't one right answer, as people have different priorities and Mods have different strengths. You need to consider the trade-offs between the mods to find the right fit for you.
Good Luck
