I'm about to add a UHF antenna to our place on the eastern side Glendowie, and I'm going to try and put the antenna in the roof cavity (colour-steel roof), but right up by a plasterboard gable that opens directly towards the Sky Tower.

 

So to give myself the best shot at pulling this off, I figured I might as well get the highest gain antenna I could find, and if I get no luck in the roof I'll go with a pole off the roof.

 

So I'm selecting between a 43 Element and 91 Element antenna and just wondering if there is such a thing as too much gain? Do I need to be careful getting a 91 element beast (apart from the size)?