ChillyW, so you understand, bedding must be a perfect fit to be advantageous. Any gaps negates its value. The action sits in the bedding as a glove fit under zero stress or bending. The action cannot be moved by hand in any direction and may require some effort to separate action and stock.
In the old days, stockmakers would spend weeks skimming the surface so that the metal to wood fit was perfect. Today, with epoxy bedding compounds, that task is simple IF done properly.
So when a company says that their bedding is CNC machined, consumers assume that they are built to exact standards. They are, but what exactly are their standards.
There is tolerance in all manufacturing so unless, the stock company machines the bedding off your actions dimensions, they are simple using robotics to get them in the general ball park.
With most Alum beds, that is taken to the extreme with usually big gaps and spaces. Guarantees a drop in fit and most will not have a clue if it is good or bad. Cheaper too. Besides could you imagine the screams from gunsmiths if the stock company erred on the small side. How do you inlet hardened alloy by hand? Besides, everyone knows they need to torque the crap out of those screws for that "tactical" fit.
As a rule, unless inletted by an old school master stockbuilder (ie cost a small fortune), bedding any and all stocks will pay dividends.
For the question about pillars, these will help eliminate the crushing of the wood stock. Usually not a big deal in quality composite stocks since the material used is already dense and hard.
The pillars still have to be sized properly so that the screw heads bottom on the pillar, not the stock or action.
Whether the hole in the pillars should be a tight or loose fit will depend if the bedding is done properly. If done properly, a loose fit is fine as there is no lateral load on the action screws - all load is in the bedding and recoil lug mortise. The action screw simply keeps the action and stock from falling apart.
If done improperly, send it back to get redone.
If a stock is very well bedded, it can be fired without any action screws with very good accuracy. It will eventually shake itself apart but is a great test of the bedding. Same point of impact, etc.
Jerry