Hi Nat, i don't really know, I'm new to it all myself.
I'm happy to give them the benefit of the doubt for the time being. I got an email response regarding my prices displaying incorrectly and it would seem that they are struggling a bit at the moment but they are working on it.
The only thing that stops me using Vendio is that I don't like their scrolling gallery, and I'm reluctant to pay for something I don't like. It stops scrolling permanently at the first click with no way to resume it, the text is hard to read and only appears briefly, non-square images have ugly white borders, and the category search is a virtually useless feature for most sellers whose products are buried deep in only one or two categories anyway (and I sell niche products which bear little resemblance to the main category header anyway).
The Auctiva gallery looks better with my pics, and I can hide repetitive items which is an excellent feature for me (Vendio looks boring with so many similar items scrolling past). The only real problems with the Auctiva gallery (apart from current glitchiness) are the links to my 'Auctiva' shop (I have an eBay shop which I want people to use) and it would appear that you can't use the code on your own web pages.
One thing I have found is that if you have more than one example of your gallery open at any time, you will get a lot more problems. I think it's just having them open on the same machine that's the problem.
The problem with writing your own gallery code is that you need to run it in conjunction with a web server - you can't have it as a self-contained script as that would violate eBay's rules for keyword spamming (all your other item titles would come up in a search).
But let me know if you find any other options!
Cheers,
Neil