Sadly, I don't think this is boring... Guess I've got to get a life...
Quick observation having to do with the US regs and the AIM: 91.215 says that when you're in airspace requiring a transponder, the transponder has to be "operated." Ok. Cryptic.
So, looking at the AIM (4-19(e)(1)) we find:
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When making routine code changes, pilots should avoid inadvertent selection of Codes 7500, 7600 or 7700 thereby causing momentary false alarms at automated ground facilities. For example, when switching from Code 2700 to Code 7200, switch first to 2200 then to 7200, NOT to 7700 and then 7200. This procedure applies to nondiscrete Code 7500 and all discrete codes in the 7600 and 7700 series (i.e. 7600-7677, 7700-7777) which will trigger special indicators in automated facilities. Only nondiscrete Code 7500 will be decoded as the hijack code.
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Of course, the AIM is NOT regulatory. Still, I get the impression that the FAA's position on this is that you shouldn't go to standby when changing codes. If they WERE suggesting standby, then there'd be no need to remind us about the potential for momentary excitement should we run through any of these codes (assuming, of course, that this was carefully thought through!).
I, for one, have seen "momentary false alarms" come from inadvertent emergency codes, and although it got my attention, it pretty quickly became obvious that the pilot was simply cycling through the code on his or her way to the assigned code (and if in doubt, I asked...). I've come to expect this from time to time, in the same way that I've come to expect to see a pilot cycle through a code assigned to an aircraft that was just about to depart--resulting in the computer tagging the aircraft I was identifying with the data block of the aircraft which had not yet departed. Perhaps this would mean that I would have to suspend the track of the departure until he/she really DOES depart, but again, not the end of the world. In the long run I'd prefer to see that secondary target associated with the primary as the code was being changed.
For instance, assume you're VFR squawking 1200 with Mode C and you call me up for some radar service. As I dig up a code for you I'm looking for your 1200 code where you said you were at. If you go to standby to enter the code, then your secondary target and altitude go away. In most cases this is probably not an issue. However, if I see a target start changing codes, there is the possibility I can help both of us out. It helps me because I can start to plan--obviously you're not identified until we dance the dance, but I've got a pretty good clue that I'm looking at you. This helps YOU because I may be working or observing traffic near you and as I see you come out of 1200 I can say something like "possible VFR traffic twelve o'clock less than a mile opposite direction altitude indicates 3200." If you go to standby, I don't know whether you are my customer or whether the Mode 3/A on a VFR target has simply gone away (as is so often the case). In that case, I can see the guy that's going to hit you, but I can't see you (well, maybe a primary, but you get the drift).
Of course, these are just MY thoughts. Give an old guy a break. I'm retired.
Dave