I have digital gear (Axe FX, Eleven Rack, bunch of pedals) and analog gear. I still prefer analog stuff over digital when I'm playing pero minsan hindi viable gumamit ng analog (e.g. practicing in an apartment, quick recording)
While my Axe FX can emulate certain amp sounds, I still can feel the lag in between the moment the pick hit the strings and the sound that comes out from the speaker (or headphones) BUT the lag not as bad as the digital gear that was available 10 years ago (I still remember my Zoom GFX-4. What a crappy piece of gear
). I have compared my Mesa Boogie, Marshall and Fender amps to my Axe FX and while the sound from the Axe FX is convincing,
the dynamics is still not there (the pick attack is articulate and immediate with a Mesa Boogie Mark V).
And as a programmer (I did some microcontroller programming in the past), I have a bit of understanding of the issues with digital amp simulation.
The first source of problem is the AD and DA conversions. This is when an analog signal (the millivolts that comes out from pickups when you hit a string) is converted to zeros and ones (digital information) and vice versa. The sampling rate (where for example, one second of sound is divided into smaller segments for digital conversion) and sampling resolution (the segment is mapped to a digital value) is the first source of the lag.
The second source of the lag is the MIPS (or speed) of the processor and the software code that is running on the gear.
While all of the DAC/ADC and processing can happen in milli or microseconds, there will always be some sort of lag when processing linear information (and hence digital effects lack immediate dynamics and articulation).
I'm okay with time based digitals effects (delay, reverb, chorus) because in most cases the output is the original analog sound (dry) mixed with the digital effect (wet). In this case, lag does not really matter unless you love the inconsistencies and noise of analog time based effects (e.g. tape delay).
With recordings, all the stuff we listen to nowadays are in digital form anyway so it does not matter anymore if a music is recorded with analog or digital gear.
My two cents