ipayment is horrendous. You'd do best to avoid them at all costs, as it will cost you out the wazoo when they tighten the screws. Just google "iPayment" complaints" and watch the joy.
My personal experience was they charged nearly FIVE PERCENT on all cards, they'd randomly insert extra fees ( oh, but they say you could have opted out IF you'd known/ been notified about them) and my personal favorite: Sending a letter with no date, to tell you about a pile of fees you were liable for in the two months previous . Mind you, this letter comes AFTER those months have passed, so there's nothing you can do to get rid of the fees. They'll tell you "It's in your contract. Too bad."
Too bad iPyament sucks! Tell the world!