do people use tri spoke track wheels on the road in day to day riding?
what are the pro's and cons?

I know the answer to the first question: yes I have recently riden with two different people sporting tri carbon wheels on the every day ride.

CON:

If that ish breaks while you're out and about, you're walking for sure, whereas with regular spokes, you can spare a few before things get too dicey. Also, repairing a broken spoke is a way more complicated and expensive endeavor.

on a lot of them i dont think you can even repair a broken "spoke" can you??

And if one of three spokes breaks, you are going to greet the pavement in a hurry.

I have a carbon Zipp tri spoke rear on my Motobacane.
I need a carbon brake pad to run the matching front wheel.
It's pretty quiet and the hub is custom built, possibly by White Industry.

(I eBay.)

If they are Track specific wheels they will be of light construction and not designed to take a daily road pounding, there are road carbon wheels which are designed for that purpose.

and i guess that having a tub (which most tri spoke wheels seem to have) would be pretty annoying if you got a punture out on the streets.
they are also very very expensive......but, they do look cool

Unless you're riding on pavé you're not gonna break a trispoke. And if you have a well-built wire wheel it won't break either. Mute point.

Loads of people use tubs on their everyday bike, myself included. Carrying a spare tub may take up a bit more room than a tube or patch kits, and changing it is a hassle whatever type of set-up you run. Flats suck, mute point.

However, posh expensive carbon is always going to be a theif magnet, especially wheels since you never see them on the street, just on TV. But if you're doing a club run and not locking up for any length of time that's not really a problem.

Your only other real problem will be crosswinds. People often complain of the sail area of trispokes, and in a strong cross wind it could make you unstable or cause a fall. But for the most part a wind that strong would be a problem anyway. If you were going for a disk I'd advise against it, but a pair of trispokes would be fine. And a chick magnet to boot

i ride with a tri-spoke in the front and it always takes a little getting used-to in a crosswind. there is definitely a difference in handling.

I use a spinergy 4 spoke carbon wheel on the front of my fixie.

Goes good, but then, I don't hop gutters too often.