The correct answer is not to use inline XSLT. This displays a basic lack of skills with the mapping tool.
I don’t agree with this statement – using inline XSLT is perfectly acceptable in this situation. The solution you have proposed is overly complex and will be a maintenance nightmare! In fact, I personally don’t like the mapper and prefer to use entriely custom XSLT when doing anything that is non-trivial – XSLT is suscint and easily readable, not requiring an understanding of the BizTalk mapper before maintaining the code. The solution you have proposed is overkill, IMHO.
However, at the end of the day it is upto the poster of the original question how they wish to proceed with the desired solution: they now have two possible options to help implement the solution.
Regards, Nick.