These adhesive plates are perfect for any boss sized pedal, to affix to a Temple Audio board, mine is a Duo 24. Personally I recommend using 2 x medium plates for a big pedal, such as a preamp or a DI, rather than 1 x large, as rubber feet usually get in the way of the large pedal plates, in my experience anyway. Also having 2 x secure points fastening the pedal to the board seems preferable over 1.
The quality is quite high, and I cannot see it ever becoming a case where my pedals will easily become unfastened from the board. I can recommend before fastening to the board, to clearly mark out where you want your pedals to go, keeping specifically in mind, the input and output jacks of all pedals, along with power points, as you want a little bit of manoeuvrability with cables etc. Also, I'd recommend palcing the plates on the board first, and slowly lowering the pedal down on to the adhesive rather than fastening the adhesive plate first. It just seems that little bit easier.
With the medium plates, try to fix it to the bottom of the pedal, that is, where you will actually be placing most weight on the pedal with your foot.