Not sure how much stop and go traffic you will be driving in, but lack of low end torque (in this case, below 3,000 rpm) I find annoying in any car. My WRX (yes apples to oranges here) was horrible in stop and go. I tired of it quickly. In this regard, you will find the boxster nicer.
If you really worried about reliability, get an S2000. I can't stand reading about people who complain about cars that break down. Yes, the Boxster can break down, and may break down more often than an S2000. I guess this is why people read consumer reports
However, a Boxster is pretty easy to work on and many out here have purchased aftermarket warranties and have been thankful they have done so.
You only live once. Why have a regret. Your last line says it all.. A Honda isn't a Porsche.