I've been chasing this issue down for a while, but have not had a definitive answer from My Republic until today.
The answer is this.
No matter if you have a residential or business plan, MyRepublic will charge you an additional $20 per month to set up a PTR/Pointer/Reverse DNS record.
There is no plan that includes this, and they don't seem willing to negotiate the price.
I've requested that the person responsible for this decision call me to please explain, but I haven't heard anything yet.
Anyway, just though I'd mention this here as adding $20 a month will affect your decision to go with MR if you require a PTR.