Hellboy44,
I would strongly suggest that if you do purchase the headset mic, buy it from a retailer that has a liberal return policy. Some retailers will not allow you to return mics, most claiming health department issues. In reality, there are NO health department regulations pertaining to microphones--NONE! Most of this is store policy.
When I purchased the Countryman E6 it was based upon two things, what I read on this forum, and hearing the mic used by a minister in a large church. Yes, he did sing, and he was using a Bose system, and the mic was very clear and distinct, features which I thought would be preferable. However, what I failed to hear was the mic had no depth whatsoever. It was very thin sounding and the feedback problem, even with lots of EQ changes, was impossible to work with. I sent it back for a full refund.
Mics used in live performances, particularly when PA systems are in close proximity, must have either super-cardiod or hyper-cardiod patterns in order to prevent feedback problems. This is why for so many years the Shure SM58 was considered the Gold Standard of vocal mics. By today's standards it is still a fairly good, handheld mic. \
The best headset mics, however, are usually those that must be positioned directly in front of the mouth, and often touching the lips. Additionally, in order to get the best low level response, and still be feedback resistant, the mic head must still be somewhat larger than most performers would like. Keep in mind that Garth Broos, Madonna, and a host of others are using the Crown CM-311A. They use it because it makes them sound good. Me too!
Good luck on whatever mic you decide upon,
Gary