My understanding of this form of Mg is that it doesn't dissociate in the gut, that is, you can take it at high doses and it will 1. (pretty much) all be absorbed, and 2. won't cause diarrhoea at the therapeutic dose. Other Mg's can draw water into the bowel which = runny stools. This form of Mg doesn't do that.
Metagenics make some excellent, well researched and well produced products, this product is one of their biggest sellers nation-wide - its a great product but Metagenics are not an inexpensive brand - from experience they are the most expensive 'prac only' brand. They do an absolutely fantastic liquid fish oil that is actually really tasty but again, that sucker aint cheap. Its a real shame - they do spend a lot of money on the glossy stuff which makes an expensive end product.
Maybe you could try the whole container and then do the same period of time with another - You know, the old self experiment scenario. Also, your naturopath should be able to answer this question for you so don't be afraid to ask him/her - it's a legitimate question and they should know the answer. If you end up liking it you need to make fast friends with someone who has a Metagenics account (often chiros, some doctors etc) and do a deal with them! ie trade wholesale priced products for 'xyz'.!
Good luck, hope this helps