Yes, the gain in balanced mode is especially high, and that can contribute to a discernable noise floor. It's the white-noise kind of noise (i.e. "ssshhh"), which I find far less offensive than any kind of hum or buzz.
It just depends on your downstream gear - it will show up to varying degrees on sensitive amps and efficient speakers. For reference, my Apollos are 250 Watts @ 1 Volt (very sensitive) and speakers are 93dB @ 1 Watt (fairly efficient). Run the same high line-gain into 250 Watts @ 2V and 87dB/ Watt speakers (a -12dB net swing); I'd bet it will be dead quiet even at very close distances. No 1 line gain is optimal for all systems.
I do run balanced mode. Still, as quiet as my vinyl source is with a Koetsu Platinum (the quietest cart I've had), the vinyl is still the sole determinant of noise floor in my system - so the bit of noise from the Hera's high gain is a non-factor to me. On a CD, it would just depend on the recording's noise floor and your sensitivity to this sort of thing. On a related note, running 5751 instead of 12AX7 in the Apollos helps this by about 1-2dB.
The gain factor is absolutely worth keeping in mind if you've got super efficient speakers >= 97dB; 25+dB of line gain is just not a good match for that, unless you're trying to make up for a very low output source (e.g. a low MC running through an MM stage).
The noise floor doesn't affect the imaging and resolution to my ears (again, the II is a sonic improvement over the I in these areas, despite the much higher gain); but then I've never been a believer that prodigious noise floor specs were necessary for these attributes, once you've got it down to a reasonable level.
