Yup, definately. You could do this with template sets you know. Have a simple template set, and an advanced template set. Strip out all the features you don't want in the simple one, and then users can go to their profile and switch to the advanced one if they want more features.
You can also use template inheritance so that you don't duplicate files (look at default_top template set - it only replaces a few files, the rest it inherits from default).
Cheers,
Alex
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