Frankly, I'll bet the call to ICA will give you nothing. They aren't going to divulge anything about someones chances. You should know better than that. Too much anecdotal evidence to the contrary.
It is not about chances, it's about a persons eligibility for PR changing, As the person is eligible for PR now and they can apply under the skills scheme, which secures them if ever they divorce too, getting PR under the spouse sponsorship is a little reckless to say the least.
They may not be eligible for PR until after 2 years of marriage, so it's not about chance. If you want to take the risks involved for chance, then i would agree a married family stand more chance
But about circumstances changing which delays the application, the chances will be the same whatever, even after 6 months wait. So the only question ICA need to answer is do circumstance for PR application change when one gets married, does the persons eligibilty change to 2 more years wait.
I would think so, as there is a period of 4 years wait for a Singaporeans spouse to get citizenship for example, becuase they are not going to issue a PR unless the person has first had an LTVSP issued for a period of time and that time for an LTVSP application to PR is 2 years to get PR and 2 as a PR before citizenship application.
Standing operation procedure would indicate, that an S pass person who gets married in Singapore has not been through the family immigration procedure from Malaysia to Singapore and from an immigration point of view I would say, the S pass applicant may have to be repatriated to home country before family applications for spouses for LTVSP pass is applied for. I don't know.
As long has she works on S pass, she is independent, and not a dependant even though married so she is not entitled for the LTVSP pass, until the S pass is forfeited. It is in between these times of waiting that problems may occur, as marriage does not give the right of abode, only immigration process.
If it was me in his shoes i wouldn't take it for granted, that getting married will allow the spouse to get PR anytime soon, a minimum 2 years as man and wife due to circumstances changing.
There is a saving of 18 months at least if she can get PR under her S pass criteria, because the future spouse has already been here over 2 years, you want to throw that saving away for what.
Doesn't make any sense to me unless you want the wife repatriated after divorce.