Product gets very poor reviews. It is not really a 'soil' - more of an amendment - and the label recommends it be mixed with regular garden soil rather than used as a standalone product. Those who used it for raised beds reported uniformly unsatisfactory results. Personally, I have not found any qualities in ANY Miracle Gro soil product to recommend them.
Only 20cf of soil needed? Must not be very large beds. For the $50 or so the MG will cost, you should be able to get several pick-up loads of good soil from your nursery or bulk soil provider.
