Not to complicate things too much, but there is a third, less popular, option and that is to mount it on your backstay. AN EXAMPLE
I thought about this, but two things on my boat. Beyond the price (the scanstrut is $1400!!!), I the following worry me:
1) I have a split backstay, which may not have the wire diameter (therefore strength) to hold up the mount back there.
2) Like my feedback on mast mount, I'd like a multi-function installation that can support the radar for one, but also the wind gen. Unless someone is aware of backstay mounting brackets for wind-gens too!!!