I have never used a regulator for ignition but have heard of some problems with certain brands and types of regulators. The problem seems to be the pulsing nature of the ignition. Though the average current requirements are low, the ignition module requires a fairly high current for a very short period of time for each spark cycle. If buying a regulator, I'd check closely with the mfgr. to make sure it was suitable for this application.

Many of us have eliminated the ignition battery completely by using something like the very reliable TechAero Ignition Battery Eliminator Circuit .. IBEC. These are in very wide use now and offer features such as selectable voltage output, peak current limiting, power isolation from the receiver battery, ignition cut-off from the transmitter, etc. just to name a few features.

Some people still don't trust running the ignition off the receiver battery but many others such as myself find they work excellent and actually reduce the number of possible failure points in the circuits. Check them out here .....

http://www.tech-aero.net/ultra-ibec