Heehee, just a few comments.
That cake recipe is fine. However, I disagree that it doesn't matter what the cake texture is, the dowels do the supporting. That is not totally correct. The cake needs to have a texture that is either spongey or dense to support the dowelling in order to be able to support the other tiers.
In a sponge cake or angel food type of cake, the cakes themselves are not heavy, so what they are supporting isn't as heavy.
However if you use a cake mix as per instructions and have several layers stacked, you are taking a chance on the support. This is most especially true with topsy turvy cakes and such.
So if you put a whole pile more dowels that you would normally, yes they will help support. But if you go with the normal amount of dowels and have large cakes and the cakes are covered with fondant or are of a lot of weight and the cakes are not dense enough to support the weight, well the dowelling only helps to a certain degree. What can happen is you can have an earthquake effect where the cake actually cracks around the dowels because it is not dense enough to support the dowels or the other cakes.
I think that generally if you look at any books on stacking cakes, they nearly always recommend that you use dense or pound type cakes. THis becomes more of an issue, the larger and heavier and more tiers the cakes has.
I know of several folks with a lot of experience, myself included, that have experimented with this and have had disasters when using cake mixes as per the box instructions even though the cakes were well boarded and dowelled and levelled and the base was supportive. Interestingly, the middle tier was where the issues with cracking occured, not the bottom tier and not the higher tiers. What happened was that the cake itself cracked where the dowels were.
Hugs Squirrelly Cakes