THAT corp 4320 vs. 4315 in a compressor

[mordechai]

I noodled with the Keeley compressor pro that uses the 4320 chip from THAT corp.  It's really quiet and clean.  I'd like to build up a more basic/simple compressor using this chip, so I visited their site.  They have a few neat pre-designed compressor circuits as points of departure for both the 4320 and the 4315.  I actually like their 4315 circuit design a bit more than the 4320 designs they have up there...the 4315 has a variable attack and release design here: 

http://www.thatcorp.com/pedals/4315%20Guitar%20Compressor%20with%20Variable%20Attack%20and%20Release%20r0A.1.pdf

I contacted one of the people at the company to inquire about whether the 4315 and the 4320 are pretty close in terms of quiet operation, and they replied that  the difference in the noise spec is about 0.5 dB -- the 4320 is -98dB and the 4315 is -97.5dB.

This technology is pretty new to me, and in fact so are compressors (other than some of the basic vactrol-based circuits I've built).  The difference between the 4315 and the 4320 seems very slight to me, but I don't know if I'm taking enough factors into consideration when coming to any conclusions about actual performance. 

What do you all think?  Is the difference in noise specs between the 4320 and the 4315 significant enough that it warrants adapting the 4315 compressor circuit above to use the 4320, or do you think the difference is sufficiently small (or negligible) that I can just build on that schematic while still using the 4315?

[Digital Larry]

I would not make any design decision based on on 0.5 dB spec difference.

Supposedly 1 dB is the just-noticeable-difference.

Also, as far as guitar stuff goes, I'm less worried these days about it being noiseless and more concerned about it not having some abrupt threshold into distortion that makes me not want to use it.