Hi, I am going to be making a 3 tiered square wedding cake with flowers beween each tier which I will be assembling at the venue. I need to find out which is the most safest way to stack it. I have a book which states that blocking with a styrafoam 4 inches smaller than the cake above and putting dowels at each corner is the safest. Today I visited a cake decorating shop and asked a proffesional cake maker and she said that she would have used the dowels as below:-
http://imaginativeicing.co.uk/store/Pillar-Spiked-Crystal-Look-9-Pack-of-4.html

which one is best or doesn't it matter?

Thanks

Either works, however, the styrofoam would be more safe/stable simply because it has more surface area for support. (Be sure to use a plate or board under the foam to prevent your foam from being pierced by the support system.)

It's great that you're assembling at the venue. In a rare occasion that the table is bumped or moved, either could topple over, but the spiked pillars are more likely to wobble or rip through the cake. The styrofoam wouldn't rip through cake, but could potentially wobble since the larger cakes on foam is top heavy. (Be sure to stick it all together with BC, RI, chocolate, or your choice of tape or "glue" where necessary. Also, for added assurance to help prevent the tiers from sliding apart from one another during a catastrophe, you can use several thin skewers to keep cake on foam and foam on cake.)

I have only ever used (the whole two times I've made a tiered cake) the single plate system - and I will only ever use this! It is so wonderfully secure and takes care of so much stress!!

If you have time on your side purchase Successful Stacking by Sharon Zambito. I found it very helpful.

CWR, if I was to use the stryaform system, will a 2 inch syrafoam board be able to support a 6 inch cake on top? The book states that you have to have the styrafoam 4 inches smaller to allow for 2 inch flowers on each side of the cake. Will this be enough support?