Outside of my above reply there are none that I am aware of (though I am sure that other issues may exist) but this is the biggest problem people switching from classic to .NET run into.
In so far as, is this practice advisible, that needs to be determined by the programmer/organization because of the time needed to convert legacy ASP code into .NET it may be more cost effective for the agency to have the programmer pass around values via the query string or save them to a database but, in the long run, this doesn't FIX the problem; its just a band-aid to temporarily solve the problem.
IMHO pick one technology or the other and stick with it.
I will only tell you how to do it, not do it for you.
Unless, of course, you want to hire me to do work for you.
^^Thats my signature