For all of the work that goes into "Making themes to suit this browser or that one", wouldn't it be easier to have some referrer script that recognises the users browser version or type and auto-redirect them to a theme that's made to be strictly compatible with the old browsers?

Like IE 6,7 and 8.

Much like a re-direct to LoFi?  

Oh! and by the way, currently the latest FF has lost cursor focus with many wysiwyg editors and some "Star Rating Applications", while the latest Opera is having lots of problems with loading flash files. Chrome can't handle multiple td cells unless the unusual practice of fixing widths with the table is used. ex: <table width="600px" because not even 60% will work.

All of which, drove me nuts.
Source: Google!  

  Browsers!

In my opinion best thing to do is keeping the site layout as simple as possible without nesting too many cells and tables (where possible of course).

From my small experience it's much easier to maintain a single style instead of maintain many.