If you have a typical flatbed cutter you will likely have a 6mm collet.
There are some good options for coated tooling in that diameter.
I would recommend to use 8mm-10mm diameter tooling.
These larger diameters will increase edge quality but will reduce intricate details.
I typically use tooling from a variety of vendors including VTX Tools, Crowne Norge, Toolstoday and Superior Carbide.
Coating on a tool is nice.
ACM like dibond can be cleanly cut with a variety of bits for a variety of edge quality finishes.
You are going to find some variances in aluminum depending on where you get it.
Alloy type/composition is key when looking at tooling.
Online stores for example have a wide selection of more or less wholesale options.
The problem with similar eshops is that soft premium alloy types cut very clean, and that may not be what you are getting.
Cheaper alloys have different compositions, are harder and provide some challenges.
For a comparative example.
Find a comparable thickness panel from Chromaluxe and two other same size sheets from 2 other vendors.
Its likely that the luxe panel will route smoothly, quieter, smoother and the bit will last longer.
One if not both of the sheets from someone else might have a louder shriek to the cutting or the chips fuse with the tip of the bit.
You can still get some good edges but you will also probably have decreased tool life.
This will cause a rough tear like cut or heavy burrs.
Fusing of metal to the tip of the bit is reduced with coated tools as well as misting systems.
Misting systems are great depending on the application and misting solution used.
This can be messy and depending on your process and graphics, this might not be the best choice.
The closer to .125" (1/8") you get with all metal, the less effective routers can be especially with the HF (high Frequency) router types.
Spindles that can reach 55k to 100k RPMS have a high frequency but low torque.
Spindles typically from 18k to 24k RPMs are high torque options.
Just because your 1KW, 1.8KW, 3KW, 3.6KW router spindles are powerful, it doesn't mean its the most efficient for all material types.
Compounding this is the standard 6mm collets that are commonly used.
At slightly under 1/4" you may have a 2.5" OAL bit where close to 1.25" of it is sticking out of the chuck.
On this .08 example, you are exerting a good amount of force just on the tip.
A variety of factors can reduce edge quality, tool life and sound during operation.
Having a good carbide tip on your bit may give you a good "bite" when enters the material and cutting.
This can also be problematic if you nest shapes too closely as this may lead to parts lifting or shifting.
Material movement while cutting will put added stress on your tooling and in many cases cause it to break or damage you cuts.
larger diameter tooling on HF spindles does lessen the gap between high and low torque spindle options.
The larger tool will experience less deflection by the reduction of force on the tip and absorb more vibration.