You'll find the blanket follows the same profile as the shield when pulled tight, so theres very little to be gained clearance wise. I had a Reid case in my altered because the shield fouled the area where the pedals wanted to sit. The inner liner in the Reid case is a very nice solution but obviously costs more. In my slightshot, I'm using a shield again but raising my pedals up.
The whole topic of SFI certs for this stuff infuriates me. The TCI flexplate shields are so thin it's unreal and I don't understand why an aluminium trans shield needs to be re-certified. I could fabricate far better shields myself, in fact the UK MSA rules mandate SFI for engines where they are produced but allow self construction for engine where SFI stuff isn't. I'd feel a lot safe fabricating my own.