Never really bought baseball tickets through after market services, but for concerts, they are not only safe, but if you keep your eyes open and have not only patience, but the willingness to have a seat somewhere that is not your first choice, you can get some really good deals. However, you seem to have a section you really want so I'd take a look at how many are available in that section and at what price. I'd watch it for a a few days, see if any action happens and then determine my next move. If they are selling, you might want to buy one to be safe, but if not, wait and wait. Prices usually drop across the board for events that aren't sold out if you wait until an hour before the start time.
I personally like stub hub a lot. Their customer service is good to from what I've heard (I've never had an issue to need it). I'll have to check out tickpick though if they have cheaper fees. From my experience it always seemed like stubhub was cheaper and had more tickets available than other sites, especially compared to ticketmaster resale.