You said to correct you if you are wrong, so here goes.
If you look at the friction coefficient of a silicone sealant, you would be very surprised with what you would find. Now with that being said, if you compare the thickness of the sealant in relation to the friction coefficient, you will notice that there is a exponential decrease of the friction/bonding properties due to the very weak tensile strength of the silicone. When the thermal properties are taken into account you will find that silicone will actually create a stronger bond due to the flexibility and elasticity of the covalent bonds in the outer electrons of the molecule. By adding additional heat to the sealant you will find that blubber will actually be created and your machine that has this sealant on it will actually fly.
Sorry have no clue on what I just wrote, but it sounded pretty cool. Lankee, I think you are probably correct on what you said, but the sealant would have to have some bonding capabilities in order for it to seal. I sure wouldn't trust it to a pressure washer!
Just use the 3M double sided tape and you won't have any problems.