Skypilot, I've been using the ignitions that came with my engines, no modifications or "special" curves to them. BME is, however, looking into upgrading the ignition or making changes to it sometime in the future, though that may not happen as well. For right now, though, I can honestly say that there appears to be no changes necessary. All 3 of my "Xtreme" based engines (2-110's and a 106) have smooth idles after you get the carburetor set properly, and there is no noticeable "vibration" throughout the rpm range of the engine. I idle them down to 1000-1100 rpm with ease, and the planes do not buck or rattle even at that low rpm, though going lower can make things get a bit rough unless you are very keen on the low end mixture. I can't see a reason to idle below 1200 rpm, but a decently smooth, and dependable, idle is very easy to achieve as low as 900 rpm, should you desire. A lot of the problems people experience with idle quality are directly related to the quality of gas and the low-end mixture being set too rich, so that the fuel puddles or drops out of suspension and does not burn properly, resulting int a rough idle.

As for how the engine "pulses" compared to the DA100 or ZDZ80. . again, a lot of that goes back to tuning of the carburetor. The porting on the DA100 is condusive to very smooth low-end operation and mid-range, and the ZDZ-80 doesn't have a problem idling, that I've seen, though the 80 does come into a harmonic imbalance at about 2500-3500 rpm, which is normal for a single cylinder engine. If you botch the mixture on any of these engines, they are going to let you know about it with a rough idle and other things going on. Best bet is to learn to tweak those needles, and address any problems as they crop up.

Hope this helps.