Hi,
so at the end, I did buy the Shure Beta 58a - I did not find locally that many offers, Shure is quite famous and the most easy micro to find on any store...
Anyway, once I can get a Shure SM58 on almost any place we perform, I decided to go for the Shure Beta 58a, no point getting a SM58, if at the end, I would end up using the one available on stage.
So, I must say that I find the Shure Beta 58 very easy to use... it capture my voice nuances and different tones. No need to scream to get heard.... I can even cover the micro for the megaphone effect (no need to swear on me).
So, I am not very aware of all the technical terms to express it here; but overall, I have the feeling that my voice is more enhanced (anyway, I was using PG 58).
I did try some other brand, do not remember the name, which had a sound that was more warm, but I got the feeling that was too much warm and all the time, with the Beta 58, I can play around more with the micro and get different levels of sound ... if you know what I mean.
Thanks for all your help and hope my comments will help someone.
Regards,
Sérgio