In my opinion they are nothing special – It’s just the current fashion in the pole float industry. It is more important to pick the right antenna/stem material, it will have loads more impact on bait presentation that the float shape ever will.
95% of the anglers are not good enough to register a difference anyway – but the tackle industry don’t tell this as they make good money on the pole floats.
They certainly aren’t new. Some of the earliest Milo Pole floats I bought back in the 70’s were pencil floats. I agree with rik j not only floats but the vast majority of fishing accessories are made to catch anglers.
The only exceptions are poles, rods and reels and even then there is no need to keep changing them. Some of mine are donkey’s years old and still serviceable.
Seem to remember an old Dickie Carr pole fishing book with pictures of slim floats for hemp. Must be 20 years old. I mostly believe in getting feeding/presentation right – exact float shape is a way down the list for most mortals.
That said, I’d use as slim a float as the flow/tow allows. Provided you can get the bait steady it must help a little bit.
As ajb says there are times and places for them. The smaller and lighter the float the less resistance to the fish (by way of inertia) the better. Body shape is important as well.
As for whether to buy hand made or mass produced that is very much a personal matter. I wouldn’t bother too much if if it was just silvers but if carp were in the picture then the stronger floats would be better.
I like the Tamas Walter pencil floats. IMO they are brilliant. When I gave some to a well known float maker to try he also thought they were the best, and whats more used them when he was on a festival at White Acres. The larger sizes around 1gram – 1.25 are very good in the deep water at Porth. Smaller sizes .3gram -.5 are very good for silvers.