How does the yyf shutter compare with the dm2 in:
1a
5a
Thumbgrinds
Horizontal play
Spin time
How smooth play is
I dont have a shutter, but I do have a dm2. You can just tell the Shutter is better at thumb grinds. Same for horizontal, because the dm2 has a high wall, which isn’t good for horizontal.
I’m not sure about the rest, but I’ll give it a shot. I’m assuming the shutter and dm2 have similar spin times, if you have perfect technique. But the dm2 does have a high wall so the strings will rub to the sides more reducing sleep time during combos, while the shutter has a low-wall so won’t rub as much so will probably have longer spin times through combos.
The shutter is probably smoother than the dm2 because it is all metal, and most yyj tends to have slight vibe, something I notice less in most yyfs.
The shutter has a more modern shape and design which will probably be better for both 1a and 5a.
Now, don’t get me wrong, the dm2 is a great yoyo, and a classic that EVERYONE needs to AT LEAST try in their yoyo career. But, if you’re looking for the better performing yoyo the Shutter is probably a safer and better choice.
The Shutter is smoother than the Shutter…might want to edit that
I don’t know what you’re talking about 
It’s a matter of preferences.
My thoughts, even though I do prefer the DM2 better:
The Shutter can beat the DM2 in nearly all those categories.
1A, 5A, the Shutter has a more modern shape, so it has a distinct over the aging shape of the DM2. The DM2 is still well capable in both those styles.
Thumbgrinds are easier on the Shutter. Finger grinds and arm grinds are better on the Shutter as well as the plastic and aluminum on the DM2 is too smooth to be a great grinder. The Dm2 needs the cap(s) removed for ease of doing thumb grinds. The Shutter still isn’t a great grinder as the surface is rather smooth. The Shutter isn’t as smooth as other YYF’s, but still, not a great grinder.
Horizontal Play: Shutter. The shape is simply better for this type of play. Plus, there is a cup for the finger spins too. Need more proof?
Spin time? Spin time is a function of player’s skill with performing the throw properly. Both the Shutter and DM2 will give you all the spin you need and then some and more. No yoyo or bearing(or combination) will increase spin time, only practice will do that.
Smooth? It depends. The Shutter plays very smooth. The DM2 has the typical metal/plastic YYJ vibe, which for me has been very small and doesn’t bother me.