Topband: To clamp or NOT...that IS the question

[James Rodenkirch]

A friend of mine is building me a switching arrangement with a reed relay to switch between my transmit antenna and a receive delta loop to the one antenna input for my Ten Tec Jupiter (I operate at QRP levels for contests).
As an added measure of protection for the KD9SV low noise pre-amp I use with my 160/80 delta loop antenna, he believes clamping the RX antenna port or shunting to ground during TX sounds like a nice thing.  But, he's seen arguments that clamping receiver input with diodes degrades the receiver performance. He find this believable, but I don't know how true it is, e.g., he knows KD1JV claims his RX performance is achieved by using 2N7000 FETs to do T/X switching.
He has a bunch of 2N7000 and will probably use one to turn on the relay.  He can turn on another one along with the relay driver that will shunt the RX antenna port to ground but he wonders if that would degrade receiver performance.
Thoughts?  72/72, Jim Rodenkirch K9JWV