Inversion after "than"/"as"

I'd like to know (1) which of the following is the most natural and (2) whether any of the following is unnatural or ungrammatical:

(A) My system is no more expensive than yours would be.

(B) My system is no more expensive than would be yours.

(C) My system is no more expensive than would yours be.

Edit: I'm adding three more examples with "as". The same question as above.

(D) My system is expensive, as yours would be.

(E) My system is expensive, as would be yours.

(F) My system is expensive, as would yours be.

Answer

(A) My system is no more expensive than yours would be.

(B) My system is no more expensive than would be yours.

(C) My system is no more expensive than would yours be.

Version #A is a sorta default kinda version. Version #B might be preferable when the speaker wants to put a contrastive subject in end position. Version #C is ungrammatical: ". . . the subject follows the sequence would be: it cannot invert with would alone, . . ." (CGEL, page 1107).

Inversion in the comparative clause can occur under certain conditions. This topic is discussed in the 2002 reference grammar by Huddleston and Pullum et al., The Cambridge Grammar of the English Language (CGEL), page 1107.