The only export radio I've come across which sounds anything remotely like a ham HF set is a President Lincoln. However putting it on a proper radio communications test set, generating a 1kHz tone the lowest you could go with the tone audible was roughly around -125dB before the internal noise of the receiver overcame the signal which has been my experience of all the CBs I've tested on it - around 122dB give or take a couple. My Kenwood TS590 goes another 16dB lower than that. It can effectively hear a signal 40 times weaker.
Another point to note: S9 calibration of a Export radio is 100uV. S9 calibration of an amateur HF radio is 50uV.
If you're going to get into the $300-$400 range you may as well spend a little more and get a ham HF set. 100W built in with finals designed to do it and a lot more functionality especially the ability to hook up to a computer.
I looked at the price of the Lincoln 2 and the Ranger here in the UK and for another £100 or so I can get a Kenwood TS480, a 100W radio with built in ATU, or for another £100 the 200W version. It has one of the quietest receivers there is, has no known problems and has been in production for 10 years as it is still in demand with no other mobile HF set that comes anywhere close to touching it for performance.
