You need to be able to see the wav files on each track as they are recording so they are not hot. Have an input select for each track/instrument/mic being recorded.
simple as it may be, I find it really useful to see the wav while I'm recording. Its frustrating to play through a whole song only to learn that I forgot to click RECORD or to see a clipped signal.
You can't fix stupid, but you can acknowledge its existence and design products that even dummies can use.
One of the benefits to RealBand is minimal hardware and software requirements. Drawing the waveform in real time could have a side effect of changing those requirements.
One way around that issue would be to change the background color of an active track (versus just armed) and draw a straight line during recording. Once the stop recording transport button is pressed, change the track's background color to normal and generate the waveform. Additionally, the active track background color could change to a bolder color and hold that bolder color if a 0dbFS signal is recorded, thus acting like a peak indicator.
You can open the mixer window for the device being used to record and see the input levels .. plus RB does show an input level VU. So the suggestion to draw a line or trigger a color change on a clip is (often) already available in the input device software. I'd rather see the waveform drawn out as suggested.
It may require better optimization in other areas of the software to accommodate, but I like the idea.