My recommendation would be somewhere in the middle. Modify your road bike only with longer aerobars for now. Don't get the forward seat post - it's not really all that necessary. A fair number of professional triathletes don't ride steep. Budget about $100 or so for a stem, and when you get fitted, buy a stem that they recommend to dial in your fit. Only buy a tri-saddle if you feel it's absolutely necessary after you've been fitted.
I know quite a few very fast age-groupers that use fairly ordinary road bikes with clip-ons. I have a bunch of bikes, including a dedicated tri-bike. But I would never delude myself into believing that I really need it. They're just very expensive toys to keep a 42 year old kid happy.