With non-Android phones, verizon had control over allowing exchange email access. With android, they are a data pipe. I run an exchange 2010 server at home and have the cheaper data plan. I can do everything that htc's exchange integration can handle.
Before I signed up I asked my company's verizon rep about the difference and got the same non-answer.
Get the cheap plan. If you decide you are not paying enough to verizon later, you can always "upgrade".