Reflectix is not good, two layers of alum foil and plastic with air can not do much. High R Double Sided Foil Insulation sounds like it is filled with tiny plastic balls. A 14.5 R value sounds very high for just 1/4" material and the price is close to Reflectix. I would not trust either one.
Check out the tests at:
http://www.glacierbay.com/Instresult.asp
Reflectix has an Actual "R" Value of 0.67!
Vacuum Panel insulation has an Actual "R" Value of 24.06 at 1 inch, wonder how much it costs?
They have a Loose-Fill Insulation that is sprayed on, they add a little glue and water to it. This type of insulation is the best for sound deadening. Foam is rigid and it can carry sound threw the walls.