Quick question about auto sniper

Hi im AGI CRT DEX but am not sure how to answer because it would take a stefly or another free stat reset event to verify things.
But from what I have you could consider:

1. Monty with lower DEX would give lower ATK but its with AAS so I am not sure if this alone can offset the ATK loss.
I imagine something like @lv375 443 DEX monty+thimble versus 443 STR 256 DEX monty+AAS,
the question being which could give better ATK? Sorry I cant verify this right now.

2. Without VIT, my build has around 5-7k HP (last I check was on the free reset event. I wasn't max lv back then, need stefly now to see exact value). Now with 56 VIT it has 15.8k HP (I lost about 100 ATK but gained 9-10k HP, a trade-off i accepted long ago).
You'd experience the first situation.
Its also worth mentioning that Decoy HP depend on VIT, which I'd like to test if I had stefly.

Edit 1/1/2020: Tested a couple months back. Decoy HP does rise with VIT.

3. Even with max AGI, Evade is never 100% so I can still die even when I can normally evade and kill the boss quickly (like with Fred, though we have decoy, pets and pots to counter this while soloing). With low HP you'd be at a greater risk. 

4. If you use a buff set with the above then you'd need more QC.

5. May I suggest building a resist set alongside your damage set? Though it may be costly, it allows you to go for more bosses. 
When I solo, my play style differs according to who the target is.
I use damage set for those I can 1 or 2 hit but at the same time can't 1 hit me while I use the said damage set (like Beelzenom or Vida).
I use resist set on bosses who spam or have OP damage (like Wizard, Uradoom or Rita400).
I use a mix of damage and resist set for anything in between (like Fred).
In parties, I normally use the damage set but if we don't have a healer or the boss is really tough I use resist set.

Best of luck. Cheers!