I probably won't have to walk the run but I will run like 6min/km or slower; or I'll burn out after 5K.

I think I need the HRM so I can push myself to the limit (esp. on the run - except if I get side stitches again, then that's the limit)

The worst that will happen is as said above, I'll finish in maybe 3:10, 3:15 but I still won't be last. I can live with that.

The only pay off would be a sub 3h finish, no one except myself would get excited about that

did I mention I'll really have to swim if I want to break 33 minutes ...