All the wedding cakes I have made have been pound cake mixes unless they've particularly asked for a flavour such as carrot or ginger. Pound cake is quite dense but if you're doing a tiered cake it will need to be realitively solid. The top tier can afford to be lighter as it has no pressure on it!
You could put two layers of fillings through it if you wanted to have more of a dessert. It also depends on how you're covering the cake. Just buttercream will make it more dessert like whereas sugarpaste will be heavier.
I don't know the exact recipe you linked to, but I have used Nigella's buttermilk cake for cakes where I wanted a reasonably dense cake but didn't want madiera. Be careful how deep the tiers are, though - I have had cakes sag under their own weight/weight of icing before now.
The best dense chocolate cake I have come across is Green&Black's Inmate's Cake.
Both keep well - I tend to reckon 1 can bake 1 week before the event, to give time to decorate, and it will have a week after the event to be eaten up.