I just completed a test to determine if the backlight would cause the battery consumption rate to increase significantly enough to foreshorten recording time. I recorded a file using the supplied 1/8" microphone with the recorder set at 24/96 with the backlight set to "always on" and the hold button engaged. The battery consumption did not appear to be increased significantly as I had already used the MT for the Dave Mason show on Monday and had not yet recharged it since then. The test started with the battery level indicating a little below 50%. The recording of a 24/96 file lasted 57:52 min/sec at which time the auto file split function worked as designed. It did not appear to take five seconds before the meters were indicating that a file was being recorded which is a good sign.
I think that the next test I conduct will be with music which will play from my computer that is in excess of the the maximum file time. When I play back the information I can check the interval for the lapse in the recording from the original on the pc in Wavelab for an exact figure on how much of a loss we can expect to see in real life using this feature.
The battery still had a significant amount of charge left for recording if required when the test was completed. I see no reason why one could not leave the backlight "Always On" and be able to easily monitor the recording.