After a discussion with Met and Skillers, I want to know what theme everyones using, so I know whether its worth my while developing the other themes?

I use the red and black... becuase it works the most often O.o

And i dont know how to change it

You can change in UserCP.

And everyone except Met uses acidTech. Met uses prosilver. Admin CP for the win! (It tells me the numbers using each style).

ok, i dont think its worth my time atm adding new stuff to other themes then, if more people used them maybe, but atm just for one person, it seems like a waste of work

I would agree, unless it's some pretty serious feature (which I can't think of an example of, but one that a user would really need).

Linking this back to the new site... do I really need to develop two sites, one for the default theme and another to cover up:

General Error
template->_tpl_load_file(): File ./forums/styles/prosilver/template/index_site.html does not exist or is empty

Can't you lock the main site to a single style to prevent errors like that?

I'm trying but atm it doesn't want to budge

There are options for default overideable styles in the admin panel, but I've never used them.