Double bass style tuning machines.
OK, so they look bad ass, and they may or may not be easier to use than regular friction pegs. The major draw backs are as follows.
A. Added weight, at 74 grams you will feel this. With these tucked in the peg holes of my fiddle I can't support it with just my chin, I need to lift it with my arm. 74 grams does not sound like much but think of it like this: You could hold a 1 pound weight all day right? For an exercise try to hold that same weight with your arm fully extended. Good luck! (try for 10 minutes)
B. Drilling more holes in your peg box is bad idea. Eight holes weakens it enough. Also keep in mind that you are putting metal screws in that do not expand and contract with humidity, over time this will cause small cracks. They also corrode and get stuck in the peg box when you try to remove them.
C. You most often have to bush and re-drill your existing peg holes just to get them on. Further weakening the peg box.
D. God, they weigh a ton!
Banjo/Uke Style Friction Tuners
B. You don't have to drill or bush to install these. but they rarely fit perfectly and could lead to buzzes and cracks.
C. I have found these to be less reliable than regular pegs. The problem is that they apply pressure across the gap in the peg box. This puts pressure where it was not designed to go. They were really designed to retain tension through a solid piece of wood. This tension if not closely monitored could lead to a catastrophic failure in the peg box.
D. They need to be tightened constantly,
so carry a screw driver.
Roth Tension tuners
Slightly better design and weight, these are the closest to being "acceptable" alternatives to real pegs. But there are still some serious draw backs.
A. Weight again. you can feel it. But not as acutely as the all metal pegs above. I know a great fiddler who has these and she plays just fine with them, She also kept me wondering how she could tune so much faster than me without fine tuners.
B. You have to ream out the peg holes all the way in order to fit them with small cork bushings. this weakens the peg box and makes it very hard to fit regular pegs again should you want to.
C. admittedly the design is much better they apply pressure in a similar way to traditional pegs. they also look pretty good.
Finally traditional pegs. These are mostly here for weight comparison. Uncut they weigh less than half as much as the Roth pegs. They will weigh even less when they are cut down to size during fitting. As much as i don't like the humidity problems involved with them they are in my mind the best option.
As far as other options I have heard a lot of positive comments on Knilling Perfection pegs. I have yet to get my hands on a set of them, so I can't include a weight comparison or real review. I have heard they are close to real peg weight. Also they have a gear ratio that makes tuning quick. I will put up a review if and when I get some. Until then I will continue using regular pegs.