MAPS RBL+ worth it?

[Tom Combs]

Hello,

  I'm considering purchasing the RBL+ service from mail-abuse.org
  and I was wondering if people thought it was worth having.  We
  get the educational discount so it is only ~$150/yr.  I was
  thinking about getting it in transfer mode, thinking that would
  save time/resources over the query mode.  Does anyone have experience
  of comments about the maps service?   Thanks,

      --Tom Combs