I have a 12.5 inch DD barrel and low profile DD gas block. Their gas blocks are not set screw (as my barrel is not dimpled for set screws) and I know this isn’t the “preferred” method for a gas block but that being said, how much trouble is it to dimple the barrel and use a set screw style block or am I making this a bigger issue than it is? 
Is it covered/protected by a sturdy rail? If so you are probably fine to rockset and stake the screws to prevent loosening.
If you are considering adding a dimple/set screw for more reliability insurance I would just have Adco or someone pin something on. It’s not very expensive.
plans are for a DD Lite 10 or Larue 11 so yes it would be covered.
Why do you need a gas block when you remove front site?
With the FSB base removed and no gas block is used how will the gas tube mount to the barrel? The gas won’t magically get from the gas port in the barrel to the gas carrier key. FM (f***ing magic) technology is good but not that good.
So when most of these gas blocks are hidden under the rails when people remove the front site.
Is this a question or a statement?
Sorry forgot the ? It is indeed a question.
The AR is a gas gun whether it be a DI (direct impingement) or a gas piston gun. The gas that is created from a fired cartridge has to have a way to get to it’s gas system. Both DI and piston systems have gas blocks. Both provide a means of the gas to flow from the barrel to the gas tube or piston/op rod.
Example: If you take a 16" M4 barrel and remove it’s FSB and install a rail or freefloat (FF) tube which will cover the gas port in the barrel you’ll either need to shave the FSB to fit under the rail/FF tube or use a low pro gas block.