Use of mats for VTA?

What do members think of using different thickness mats as a method of changing VTA? I have been doing this for while by ear, instead of using one of the Rega VTA adjusters for a RB 250 tonearm.I believe there is a loss of arm rigidity adding a VTA adjuster into the chain.
Hi Stephan,
I've been doing that for years with excellent results for rapid VTA adjustment.
I generally swap between,Rega standard, Linn LP12,Rega P9(thickest to thinnest).My thickest mat was from an Oracle Alexandria mkV and the best use for it has been on my trusty VPI HW16 cleaning machine.
Keep in mind that each of these mats has a slightly different take on the presentation,even with identical VTA/SRA setup.
The thinner the mat, the more detailed,quicker and tighter the sound but often with a slight reduction in musical coherence and moving towards a drier outlook(sometimes beneficial).
As a baseline,I generally prefer the stock OEM Roksan mat on the Roksan Xerxes X , the Linn mat on Regas and the Linn or P9 mat on LP12's and take a great deal of care to optimise the VTA for average thickness recordings.From that starting point ,I'll then swap mats for the occassional very thin or heavy duty pressings.

Thanks for the informative response.Do you swap the mats in conjunction with a VTA adjustment on your tonearm or do you use mats alone? I have several types(6)of mat ranging from a 4mm Rega standard to 1mm "disco" mats and I iterate for height between them.I don't think that my system is good enough to exhibit the finer distinctions all that well, but I would class the mats as all "felt" types and I do have a rubber Ariston one that lends a tighter sound.I will try your suggestion about different mat materials though.stefanl
RE:"Do you swap the mats in conjunction with a VTA adjustment on your tonearm or do you use mats alone?"

I adjust as best I can for average thickness recordings with the tonearm(ie-spacers for RB's, sliding pillar adjustment for the Linn & Tabriz Zi, double adjusting collar on the Artemiz,etc).I only change mats for instances where the thickness of the recording is causing a noticeable negative sonic effect.
I'm presently using a Dynavector Karat Nova whose stylus profile is not particularly VTA sensitive.
In the past and when I used the mat exchanging ploy to greatest effect was while I used Benzes and VdH's with their ultra sensitive Gyger and VdH styli.
Can you swap mats while the record is playing? Just kidding. Would be sort of like that trick were the tablecloth is very quickly pulled and all the china and things stay on the table... trouble is the spindle, I guess. More seriously, this seems like a simple and ingeneous solution to the VTA issue.
If you want to really fine tune VTA by this method, Ringmat sells a set of variable thickness VTA shims. Supposedly really good, as they should be for the fairly outlandish price.

How about sheets of mylar in varying thicknesses. Just cut them to shape yourself. Should cost next to nothing.