I once frustrated the Grandstream marketing folks at a tradeshow. The year was around 2007, and the show was SuperComm. (I think.) My exposure to GrandStream was the BudgeTone and the HandyTone. We had tested both devices, and made them work, but neither of them was something we could recommend.
I asked the booth-staffers whether they had any business phones. They pointed at something with novelty-oversized pushbuttons and grumped, "Business phones? Of course! We've always had business phones. Look right here."
Time has passed, and they've since released the GXP-2100 phone. It looks a lot more like a traditional business phone. It has a nice, standard feel in a phone.
This is a phone with considering for your deployment. But I'm concerned that the Cost Engineering is still running the show at Grandstream's handset-design department