I am thinking of upgrading my pedals before I attempt a half ironman next summer. the bike that I have is an older model road bike and while platform pedals have been sufficient so far I have a hard time staying on the damn things. I've thought about just using toe clips but they kind of scare me, when I was a kid I twisted my ankle pretty bad trying to get out of them and I've herd clipless pedals are easier. while I did buy this bike for racing it has become my daily transport and I would really like to keep the ability to use platforms. I thought about the spd hybrid pedals (a530, m324) but what kind of shoes would be compatible? I can't find many tri shoes that work with this type of cleat. I've also given some thought to the speedplay zero pedals and using the platformer attachment for my short rides. any thoughts on which way to go? pros cons either way, or is there another option?

My TR31 Shimano shoes are great and would work.

I think your on the right track! Speedplay Zero with "keep on cleat covers". Have them for my road bike and my tandem. Never have to look down and fiddle with the peddles. Just place the shoe and stomp down. The keep on cleat covers kind of guide the shoe onto the peddle. Also it's much easier to run in transition with the covers and keeps your cleats from being trashed.
[h=1][/h]

now that I know about these stay on covers I think I'm sold on the speedplays.