Digital trim/level give much better chance that all channels have inherent known/precision tracking ability. Possible to set exact 'dB' adjustments.
If you're talking about digital control of the analog input circuitry, that makes sense, but digital control of the digital circuitry is what you should do in your DAW after (well, assuming you don't just play stuff back from the recorder as is). Digitally changing the value of the bits being recorded to the digital recording medium during recording is absolutely the same as digitally changing them during playback or editing on the way back from the medium - where you get a chance to change your mind.
From that perspective, you're right about applying channel (mic input) gain tweaking in post DAW. And I see no reason this is any different than having in-deck fixed trim tracking ability.
FR-2LE is one of the decks I've not yet bench/features tested. And maybe SD 2-channel decks have this same ability, but not 744T with only 2 out of 4 channels having in-deck 'mic preamp' input/possible trim/then master up/down level setting tracking feature.
With most these digital decks using at least one stage of VCA (voltage controlled amplifier) in each recording channel, or direct analog signal into a single CODEC IC with internal analog amps also being digitally controlled in some manner, I personally see this an
improvement over resistive-mechanical knob/fader channel gain for most accurate up/down level adjustments.
I did have chance to work original Fostex FR-2 deck, and this with resistive knob first gain stage trim using a very small knob, and then larger dual locking master level adjust knob on deck's front panel.
So if I remember correctly, this deck has two possible channel offset features, top-panel individual channel trims, and front panel master with locking tracking ability, but of dubious channel match accuracy.
I remember thinking FR-2 has too much room for tracking error, and no easy way to adjust absolute channel gain precision if mics that were
already precision matched
unless all the way or down (at the rotation stops) of the small top-panel channel trim knobs.
For consistent balanced stereo recording with
known applied 2-channel tracking, such 'analog' type controls are most problematic, with 'stepped' digital gain control having much better tracking accuracy.
For that reason, I personally avoid the use of knob gain controls on my
all analog preamplifiers. Instead use precision
fixed resistor network with a multiple position switch so channel gain
always with <0.1 dB channel tracking error; actually better precision than than most 'digital' systems using VCA circuitry.
