So I've had some time with my Underdog and think I have a good feel for it. Please note that I have never used any other log vape.
Aesthetically, my Underdog is 9 for 10. It's the only vape I have that is a one-off, handmade work of art. I can see why people love the log vapes and their unique wooden designs so much. The whole thing looks fantastic, from the body to the work around the heat port, to it's completely solid and rattle-free feel. It has a nice, long, detachable cord. The bottom leather seems expertly applied. There's not a rough cut or blemish on the whole thing.
The draw is very free, very unrestricted, and ideal for vaporbonging, unlike what I hear of the other log vapes. The silicone tubes get some slight acclimating too, and I think have a very faint but detectable taste which is not objectionable. Taste is otherwise quite good. I worry about the bowl's screens, replacing them will probably have a real knack to it. An Extreme Q mouthpiece works great as a mouthpiece because it has a very large mouth hole, unlike alot of glass mouthpieces, so it won't mess with airflow. A flush 14mm-19mm adapter fits the silicone and works great for vapebonging - these are like 9 bucks from many retailers such as blissville. I would like to fantasize about a all-glass stem in the future but there's nothing wrong with the silicone, and I have no reason to believe they're inferior in any way to the nylon stems used by the other logs.
Heat retention is probably 8/10, not bad at all.
Hits are dense! With my bubbler I can get vapor which is denser than the Solo with a similar heat setting.
My only complaint is that my unit runs a little too cool. I will definitely be investing in a higher voltage power supply in order to finish the bowls, or maybe get a koozie thing like some people get for other logs. That is really my only complaint at all. I think wood density and type and thickness might have alot to do with how hot each Underdog gets because the wood is the insulator, and some may need higher voltages to make really thorough extractions.
I give it an 8.5. It's a welcome addition to my vapor collection, and the single most beautiful piece of the whole lot. It was made by hand, out of three different pieces of wood, superbly fused together to house a potent vapor engine. For less than a mass manufactured affair like a DBV, it's a great vape.