They also have the two level buses for the more popular route.
I know about the Megabus crash in upstate NY but, while tragic, accidents happen. Even accidents that are caused by negligence of the driver. There have been airplane crashed due to no more than pilot error but I still fly. Looking at the statistics I would still use a Megabus if the situation called for it even though they have had a tragic accident.
Of course if that accident is enough to keep you from using it by all means don't.