To start with I know I'm wading into a debate that will never be settled. Both treble and single hooks have their virtues. I personally have used both with much success. The question of primary consideration is how you set up your spoons.
Lets take a look at the pluses and minus of both, and best ways to use singles and trebles.
Treble Hook: A treble hooks main advantage is it allows for a high hook up percentage, but.....you will experience more lost fish after the initial hook up compared to a single. Trebles have a small hook gap compared with a single, and the three hooks can, and will work against each other during a long fight. Ways to counter this problem are to use wide gap trebles with a short shank. The wide gap allows for better hook penetration, and the short shank allows the fish less torque on the spoon.
Single Hook: Specifically a siwash style single hook for spoons, and an octopus style hook on flies. The main advantage of a single is a far better catch rate after a fish is initially hooked. The large hook gap, and lack of other hooks allow greater penetration and less torque from the spoon. If you need proof, there is a reason all saltwater pelagic species are fished with single hooks, a treble wouldn't stand a chance getting the penetration necessary in a bony mouth or holding on during a multi hour fight. Other upsides include less trouble in the net, and less damage to the fish if you want to release it. The downside to a single hook is a lower hook up percentage on the intial strike. Use a 4/0 siwash hook for most spoons. Now the best of both worlds is to include the hooking ability of the treble, and the holding power of a single hook. The great thing is that can be incorporated in a fly, and is exactly what you get with a Poseidon tournament tied hook harness.
Tip of the Day: Instead of attaching the hook directly to the split ring on the bottom of the spoon attach a ball bearing swivel to the split ring than attach the hook to the swivel. This will allow the fish zero torque using the spoon, and should greatly increase your catch rate. Down size single hooks to either a 2/0 for a regular spoon or a 3/0 for a mag spoon to account for the additional length of the swivel. Fishing Report for Milwaukee - Fishing continues to remain slow averaging anywhere from 3-8 fish per trip. There are two patterns to try. The deep pattern is in 110-150 fow from the bottom up to about 75 feet. This is primarily for silver fish. If you are after the big boys than fish either the north or main gap. Work the gaps themselves and the inside and outside of the wall depending on wind direction.
It is late enough in the year that the staging kings will be by the gaps no matter the temp. The colder the water temp the more active the kings will be. Look for some colder water by this weekend after the hard NNE blow today.
Good Luck. Poseidon