The blocks do look cool, in a ghetto kind of way, but one thing I don't like about them is how much space the take up! You will quickly find that real estate underneath the tank is precious :-) You could easily replace them with a very sturdy stand of 2x4s or 2x6s (if you're paranoid). Here are plans that many reefers around the world use ->
stand plans
My 150g is held up by $75 worth of support materials.. hehe
P.S. Personally I would sort out the stand situation before you've filled the tank. Not sure if a "temporary" stand is ideal. Down the road you'll be like.. "man, i wish I had a refugium.. darnit, there's no room under the stand..", or "man I wish I had a bigger skimmer, but I need a bigger sump.. darnit, there's no room to put in a bigger sump". Would be major pain in the arse to do the stand over down the road when you've stocked your tank and have everything running smoothly. Just my 2 cents.