Because you are brewing a weizenbock, which is more caramelly/cocoa-like by nature, the banana esters will be very subdued and practically undetectable. The Weihenstephan Weizen yeast is a great strain, and probably superior IMHO. I am literally brewing a Weizenbock and fermenting with 3068 tomorrow, so just go for it!
Read my homebrew blog!
Sea Symphony Strong Ale
Limerick Session Stout, Junior/Senior Amarillo RyePA, Ralph Partigyle Bitter, Saison de Potiron
Yazoo Gerst Clone, Experimental Belgian Mild, Nelson Sauvin SMaSH bitter, Belgian IPA, Coffee Cream Stout
Relax, don't worry, have a homebrew.