The alpha processing mode in the math components vary. They seem to be designed from a guestimation about likely usage. I do not question the choices here, however it would be extremely useful if math components in general had a "Process Alpha" checkbox, which would process alpha in the same way as RGB.
Also, like suggested elsewhere, it would be useful if the alpha channel in general was HDR (like RGB). Like with RGB, components that require the 0..1 range should then clip the range.
What do you think?