In my experience with several Elite trainers (but not the Tuo directly), this is definitely a feature / bug / advantage / drawback of Elite trainers (depending on your POV).
The power for Elite in ERG mode tends to be much more variable vs. locked in compared to other brands…so if you overshoot a target, it can take longer to “settle in”. Even then, it is pretty easy to bounce around a bit over / under the target number.
Personally, I always liked it…I started calling Ergsistence mode, since it seemed to be a blend of both modes. The trianer kept me locked in within a certain range, but I could also use my feel / effort to increase / decrease the wattage.
However, for short VO2 intervals, it was definitely a challenge for the reasons you cited…therefore I would recommend for short VO2 efforts, you just do them in Resistance mode.
Tax neo 2t works fine for me. If I do resistance, I fumble around for longer than it takes the neo to adjust. For very short ones (15 seconds) I’ll go resistance but 30 seconds and longer in erg works fine on that trainer for me.
As mentioned above, all trainers struggle with erg mode on very short (30 seconds or less), steep° intervals, but some trainers struggle more than others. Your gear choice can also help quite a bit.
First, regarding gear choice, you’ll find that your trainer will probably handle interval changes better when you’re in the small chainring in the front, and a bigger cog in the back. In erg mode, your power will be the same, but the trainer fly-wheel (or equivalent) won’t need to spin as fast. This usually makes it easier for the trainer to smooth out the power, and to adjust resistance for intervals.
Second, regarding trainers, there are big differences. I had an Elite Direto that worked great in Zwift and for erg workouts with long intervals, but it was really hard to hit the targets for sprint and short VO2 intervals with big jumps. My next trainer was a Tacx Neo2 and the difference was night and day. Sprints still work best in resistance mode, but erg mode is passible, and 30 second or long intervals are no problem (in the right gear). YMMV.
j.
° by “steep”, I mean a quick drastic change in power level, rather than a gradual build-up.
Iirc from reviews the tuo had trouble holding power much higher than 220 ( maybe it was 240?) due to its wheel-on but contactless, magnetic resistance design
