Consequences of using variables declared __declspec(thread)

As a prerequisite, I am going to assume that you understand how TLS works, and in particular how __declspec(thread) variables work. There's a quite thorough treatise on the subject by Ken Johnson (better known as Skywing), who comments quite frequently on this site. The series starts here and continues for a total of 8 installments, ending here. That last page also has a table of contents so you