I got my "green card" in '93 and decided to submit to the
naturalization process in July of '07, which culminated in my
becoming a US citizen in February of '08.
Yes, I shall admit that I have been too lazy to initiate the SG
citizenship renunciation process. I still have my SG passport, and
I hear they fetch a princely sum on the black market.

As I was out of the country continuously right after the
completion of my NS, I was never called back for reservist duty.
However, I had to renew my Exit Permit annually, which was a real
hassle up until the expiration of my reservist obligations.
No SG tax liabilities here--why in blazes would I want to pay
taxes to the SG gabrament on incomed earned in the US???
Yes, I totally agree. Renewing EP every year is simply
annoying.
How many years have you been doing this? Have they ever asked
you to show documentary proof of PR status/ employment etc. I know
a few guys who renewed for a couple of years then MINDEF
started requesting for documentary proof.
Not that they do not have the proof, it just increases the
hassle.