If you have a quick google, you will find where others have quantified the effect of typical cab forward shells (e.g. Proline Bulldog and JConcepts Punisher/Finnisher). Whilst you may be surprised, I seem to recall the concensus being that as long as there was enough surface area it made a difference to the downforce on the front. Simply shoving the cab "bulge" forward isn't enough so not all cab forward shells offer enough surface area to make any difference so this is purely cosmetic.
You mention the shock tower interfering - I think this is why the original cab forward designs have such as massive raking windscreen (so it affects the air passing over the shock tower). Trimming a few mm off the rear of a wing has a noticeable difference on the handling of our buggies (esp when jumping) as can running a cab forward shell.
And a steep and angular cab forward windscreen just looks "slammed" (as the Americans say)...I wouldn't say that yours looks any prettier than a Bulldog or Finnisher shell although it looks better than the kit one
Just my opinions - don't hate me for 'em
