I have a portacath but that's because they had trouble getting a vein on the first go at chemo. I have subsequently found getting blood from my elbow crease difficult too (no problems before chemo). I had a portacath put in and it is a breeze for me but not everyone likes it. I get my blood taken from it, chemo put through it and tomorrow I will have a blood transfusion through it. It doesn't hurt (it is painful for about a week after the surgery) and the way mine has been done you can't see it when I have a bra on. I am having herceptin too so I think it was worth my while.
But for you it sounds like it has been going fine and the Herceptin won't damage your veins so why not keep going with what is working - no need for extra surgery if there is no real upside?
Good luck with your decision.
Amanda xx