Wow, that is quite a discussion. Here's my 3 cents. The NRD receivers were near the top of the heap -- especially 515 and the 545, though the last in the line (545) had to the ears of some still some audio harshness issues. I still have tow 545s and they are like riding in a Maserati. Similarly, the JRC marine radios NRD-93 and up are like a ride in a sports car (though the NRD-630, very rare -- went to DSP like the WJ 8711).
As for antennas, I have not used a MLA-30 -- I use a Wellbrook 1530 (the older LNP) and a W6LVP. I hope to test the W6 with a MLA amp box -- so far the W6LVP has been the most quiet, though at some points needs a boost from a RPA-1 or other amp box.
If the MLA-30+ gets anywhere near the W6LVP, that is quite an accomplishment for a cheap, mass-produced made-in-China loop.
I have had a 515, 525 and 93, and they looked real cool on the desk. But they were nothing special in reception capability. I mean they were very good, but if there was QRN, then it suffered. If there was no propagation for the signals I was trying to listen, they couldn't receive. They were just like any other communicate receivers. They had good audio and looked cool and made well with high quality parts.
But for NRD545, they are still very expensive here in EU, even the used ones. I am sure it is a good receiver. I have not had it before, but I read reviews that their audio is harsh, it is made of cheap plastic on the front facia, and mostly critically, they are no longer supported by the manufacturer? I mean all that glorious marketing slogan - superb serviceability with the plugin module design, but not supported by the manufacturer? Whats the point?
Not grinding axe or anything, but just my passing thought on it