B-ut one thing about the C&Ds are they are not making unsubstantiated claims where as Appion is saying they are RATED to 20 microns....and I still say SAYS WHO?
What independent nationally recognized entity rated them and what is the written standard they are measured against?
What Variables affect evac time: how aboutthings like how wet the system is, how long the line set, internal volume of eqip under evacuation, how many frickin' fitting on your evac tree, how long your hoses are, ambient atmospheric conditions, quality of pump oil, two stage rotary or pump or single stage, gas ballast or no gas ballast ect. ect.
Your CRT will let you pump down just as fast as any other as long as it is maintained. The "leaky" comment you made....one CRT rated at 200 mics and one at 20 mics (assuming it's true) will hold vacuum until it reaches its aforementioned threshold.
That's why all my vacs do not exceed 300 mics. But it does not leak from the git go just case it's rated at 200 mics.
And a 20 mics rating does not guarantee you a faster evac. Time and system condition and the variables mentioned do.