We had a visitor recently during open mat that wanted to roll no gi, he didn't have his gi with him. Everyone wears a gi during open mat. We have no gi once a week, but we wear gi pants. So I took off my gi top and rolled with the guy. He was very skilled and was putting me in danger pretty much the entire match. I was on top the whole match and managed to pass his guard twice in a 15 min roll, which was no easy task. I felt like a I should have been able to pass his guard more. My passing is very torreando/ smash pass (grab the lapel and stack) centered. I did go for the double under pass a few times, but he was able to stay on his shoulders and prevent me from passing. So my question is: Should I suggest to my instructor that we wear shorts during no gi day, or should I change the way I pass and become less dependent on using the pants?
If your training no gi then you shouldn't be grabbing the pants even if they are available, otherwise your just training 1/2 gi. Just adapt, it will make your gi game better. 
i know what you're trying to do and i'm not falling for it.
gi will make your game better, period.
stop trying to back-door-bravo us... i'm not into that shit.
or
what poster above said.
lol. im not trolling. i love the gi! seems that the suggestion is that i need to use passes that are more "universal". (no pun intended)
Modify your grips bro. Be super tight and heavy.
Maybe he was just a better BJJ player then you. Also, you should be wearing shorts while training no-gi anyway, unless you wanna copy Eddie Bravo. 
agreed that if you're wearing pants then it's half - gi and especially so if you are using/grabbing the pants
stop grabbing the pants when its no gi. Just dont do it
and learn more passes
Jits_n_Hoez -Maybe he was just a better BJJ player then you. Also, you should be wearing shorts while training no-gi anyway, unless you wanna copy Eddie Bravo.
Who wouldn't want to copy The King of No Gi...?
He won a fight, once!
Wearing pants in no gi is fine. But the advantage goes both ways. The guy with pants on benefits from the friction, therefore the other guy can use his pants for grips as per naga rules.
However I've been having much success passing toreando no gi lately, hands on top of the knees, smashing and shifting, been working great. I'm trying to expand my passing game from just stacking all the time.