Sorry for the delay getting back to you guys.. it's always a madhouse around here the day or two after a refresh lol. Taking a quick breather now though and will answer a few posts:
Dave, I've never used a VVPS. To be honest, I don't like clutter and have never really felt the need to run my dog any hotter or cooler. Am I missing out on something with the VVPS?
In your case Stu if you don't feel the need to adjust your temp up or down there's no real functional need for a VVPS. I of course have a vested interest (reduced warranty support) in as many users as possible using a VVPS if they use how I would like them to, ie standby voltage when not in use and using the lowest possible temp to get the results they want. So in your case you're getting better convenience and less clutter for the possible trade off of having a Pup need service, or need it sooner.
How much for the vvps for existing dog owners? I noticed the vvps wasnt listed on the website.
I haven't really figured out how to address all the difference aspects of this whole VVPS thing yet but the VVPSs are costing me $20/ea (incl the cable) so a break-even point for me (incl Priority shipping) would be like $25.
...When the power supply has been on for a few hours, does it get hot to the touch?
Yeah they get pretty warm, the aluminum case makes for a good heat sink which is probably good since these don't use fans for cooling.
...The downsides of the VVPS over the wall-wart? The VVPS uses more energy (due to heat and lights). Don't know how much more (maybe someone with one of those "test your appliances energy draw" plugs could do some research). The VVPS makes a annoying humming/static/squeal noise which seems to increase in volume and pitch with an increase in voltage.
Best option? Damn, I think you need to get both! I run my Dog mostly on the wall-wart, but definitely like options and the ability to tinker.
EDIT: And on the discussion of Underdog electrical supply, I could definitely use an extension cord. 6 feet is more than enough for my personal use, but another 10 feet would be awesome when passing the Dog down the couch or to the person in the rocking chair.
Not sure if or how much more power the VVPS uses but I can test that easy enough, if I can remember. Better write down lol.
So far I haven't noticed these ones making any of those static noises you mentioned so hopefully they don't. The one I sent you was a super-cheapy from ebay vs these ones I ordered which are supposed to be of higher quality. Both are from China of course but I found the vendor who makes them and ordered a couple thousand dollars worth directly. With goods from China the vendors usually build two variants, one aiming for the lowest possible price (the cheap variant) and the other aimed at a higher quality for picky customers. In this case that means a $5 model and a $15 model. I chose the $15 variant so hopefully I got what I paid for. Only time will tell I suppose.
I do think we'll be changing the options so that people can get both if they want, gotta crunch the numbers and see how to do it on the website first though.
Extension cord? >>>
http://www.underdogvapes.com/accessories/electrical/extension-cord/ 
I didn't see the VVPS option when I ordered the California Claro Walnut yesterday =[
I think yours was actually the first order to go through after we added the option. If you still have your order confirmation you can look at the options and see where you selected 'Standard Wall Wart'. I did get a couple confused emails though so I think some people (maybe you too?) either missed the option and answered on auto-pilot or just didn't know what to make of it and chose one randomly.
You did get a haiku though and not everyone gets one of those..
Good old inexpensive coils or VRM in there I guess. 
