Opinions here, not facts.
1) I see no point in a poly unless a fail means D and a pass means a commitment to R that is conditioned on continued work by both partners to heal and to R. What else can a fail mean other than that your WS has failed in the primary, sine qua non aspect of remorse/contrition?
2) That means, IMO, that a poly is appropriate only when the D/R choice comes down to 2-3 questions that can be answered only by 'yes' or no'.
3) Usually BSes have too many questions to be asked in a poly, and IMO, the important questions can't be answered with a 'yes' or a 'no'.
IOW, if you need 2-3 answers that must be yes or no, and if you're willing to D your WS if she fails the poly, do the poly now. Otherwise, wait.
I believe most human beings are better lie detectors than any machine is, especially if we have time to calibrate to a person under test. My reco is to wait until you reestablish the measure of your W.
I understand your impatience. Why else do you think 'soon' is part of my ID here? It took me seconds to realize I wanted R. Waiting to find out if I could actually get R was excruciating ... on top of the excruciating pain of knowing my W betrayed me.
But the only way I could speed up my M's resolution was to choose D, and that was certainly a potential outcome of my R actions - but D was the opposite of what I wanted.
You can't expect fast, cheap, and good in a product or in a reconciliation. In fact, when it comes to R, 'good' is necessarily slow and expensive.
*****
WRT 'reestablishing the measure of your WS', my guess is: sometime between 6 months and 2 years from d-day, maybe even sooner, the vast majority of BSes will again know when their WS is truthful and when they're lying. I agree with those who trust their guts more than their brains in this.
[This message edited by SI Staff at 6:42 PM, Thursday, December 25th]