radar questions

I read in Practical Sailor about radar, and their reccomendations were
the Furuno 1715 (? I think), and not rated as good was the 1623. I
have a race boat, and want a radar, but as small and light as possible.
While sailing aboard Derek Baylis, a Wylie Cat 65 this past weekend, I
asked the captain what he thought of the 1623, since that is what was
on board. He answered that it was the worst piece of junk for a radar
he's ever seen, and he has much experience. Here I was ready to buy
one, but now not so sure about the 1623.

A few questions. Is there another small radar that is good? Is the
quality of the radar directly related to the size of the radome? What
are the pros and cons of locating a radar on short mast aft, as many
cruisers have, or on the main mast of a sloop?

thanks for any help,

Luc