Do different Kendamas vary in size? Like, do the size of the Kens or Tamas vary in size between different models?
How often should you change a Kendama string? And what are signs that you should change it?
Lastly, what is it like to play with a sticky Tama? And which is better, the Super Stick or the ATack? I currently use a Tribute.
Idk about the first one, but you don’t need to change your Kendama string very often. Maybe when it starts badly fraying or when it breaks (obviously).
As for Super Stick vs. aTack, as far as I’ve heard, the SS is sticker. The aTack isn’t as tacky straight out of the box, but once you break it in, it takes on a tacky almost rubberized feel on the Tama. I have an aTack. It’s awesome! Another huge plus is the tama paint. It’s extremely chip resistant. Dent, yes, chip no. It’s a great ken and I highly recommend it :).
Yes they vary some kens are thicker others thinner, some tamas are heavier others lighter, same with kens some are heavier, others lighter. There is also jumbo, emperor, and performer kendamas that are large in size, as well as mini kendamas that are well… mini.
Whenever you want really they last a while, I would assume when you see breakage or tearing of threads.
3.It makes some tricks easier, basically most if not all balance tricks. I assume Atack since it gets tackier the more you play, however I suppose it is preference. If you want really sticky straight out of the box then the Super Stick, if you want greater tackiness over time then the Atack.
Good luck on you choice. 
Thank you for your answers.
The size question didn’t really matter, I was just interested.
I was considering changing the string on my Kendama before Worlds, but it is only somewhat fraying near the Ken.
And as for the sticky Tamas, I think I might get one by the end of the year. I would probably choose the ATack, since I would rather try out a Sweets.
