Ive recently moved house and have managed to do away with most of the indoor Aerials I was using for my HTPC.  Unfortunately its just not quite cutting it signal wise when Im recording more than one MUX at once (I have a HVR-2200 & another single DVB-T Card).  Im thinking a bigger aerial might help the problem?  I basically want to run no more than 4 devices off it at any one time (really only need 3).  Im not sure how old the aerial on the roof is but Im guessing approx 10-15 years so Im quite happy to replace it. 

Now as for replacements Im not sure what to get - Im thinking of one of these:

http://www.freeviewshop.co.nz/element-aerial-freeview-p-76.html
or
http://www.freeviewshop.co.nz/element-aerial-freeview-p-456.html
or
http://www.freeviewshop.co.nz/triple-folding-structure-aerial-freeview-p-594.html

I live at the Oratia end of Glen Eden (in Auckland) and have a pretty good line of sight of everything from the roof (well Im taking it for granted I do as I dont particularly like roof crawling!).  If I go for the bigger one will I hit possible problems with having too much signal or something?