According both the old and new D4 spec sheets, the before-proximity-effect response is actually pretty flat between 60Hz and 1kHz - it looks to be +/- 1. Above that it gets hot, but it's a wide rise and easy to tame. Below 60Hz, it depends on which sheet you believe - the new one shows a rolloff below 60Hz, the old one shows it solid to 40Hz, and a slower rolloff below that.
The PR40 before-proximity-effect response is flat below 2500Hz, with a very slight and gentle bump above. The bottom is solid to 40Hz, and rolls off a bit below. It would seem to have less proximity effect than most, meaning much less mud to EQ out.
The RE has no real proximity effect. It's a bit rocky above 1K, but no big deal. It's flat to ~70Hz, and rolls off below that.
So on paper - and likely in practice - none are good below the E, some aren't good below the A. But the speakers aren't either, so it may not make a difference. As to which best captures the rest of the spectrum, I think any will do a better job than most of the more popular mics (kick mics mainly), and a used D4 costs half or less what the others cost used.
This stuff didn't quite jibe with what my ears have been telling me, so I looked in to it. The PR40 is absolutely NOT flat to 40 Hz, it starts rolling off at about 100 and is down 5 dB by 50 Hz.
Here's the chart:
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The 28 Hz figure which they advertise it at appears to be about the -8 dB point. You probably get some of that back with proximity effect.
The EV starts rolling off later, but drops more steeply. It is ruler flat to 70 Hz and down 2.5 dB by 50 Hz. At the advertised 45 Hz it is down about 3 dB. The chart is in this pdf Invalid Link Removed.
The EV also has a much flatter high end. The PR40 has a pretty dramatic presence boost(like a good 10 dB or so), not unlike a 57.
Don't get me wrong, the Heil stuff is great. But the advertised numbers are a bit misleading. Heil is quoting the low end from the -8 dB point, EV from the -3 dB point. At 40 Hz you are getting more from the EV than you are from the Heil.