The snail and the snuffer represents two different approaches, easy handling/bullet-proof or clean/hightech.

You can mix the snuffers and different halyard approaches they way you like, but if you pay for the snail you are probably aiming for a clean low drag approach.

Here I compare the F18 Capricorn setup (2007) and the M20 setup.

If you do a lot of short upwind-downwind racing every second counts on the roundings. A bulletproof and simple system is the way to go, use the snuffer with everything external. If you lose a bit of upwind speed due to windage (lines, blocks and a bag hanging under the spi pole) is ok as long as you can keep up with the rest of the fleet on the first upwind.

The clean approach means that you put things internal instead. The spi halyard is led down using a tube from the front of the mast and back to the sail track and then down along the the sail track. The block and lines needed for single line hoisting is hidden in the spi pole. The bridle and line used to bend the pole in a safe driection is replace by teardrop shaped rods supporting the spi pole.

And finally the bag is removed and replaced by the snail close to the mast.

My personal selection would be the following:

M20, short upwind/downwind course, use a snuffer
M20, longer courses go for the clean concept
A-class, due to the lack of arms on normal sailors the spi manouvers are quite slow and the advantage of a snuffer would be marginal but my personal opinion is that the A-class is sensitive to windage (The A-class has the same size as an F18 but only 30% or something as righting torque)

/hakan