S35: Actually the 857 should have good audio without a amplified mic added....but it's all about preference.
I had a 100d mic and sold it quickly, just to short a stand and picked up to much back round noise for my taste.
I have several mic's I use on my Yaesu rigs:
Presently running on my FTdx3000 I have an Audio Technica T1000HE (HE/High Energy) Also have a Heil PR-781 with is on my FT-950 for now. Had it on my 3000 for quite some time, however it is a stout mic and was pulling down my boom all the time.
When I get a stronger "goose neck"....I'll go back to that.
I also have a Heil "Gold Elite" studio mic which sounds very good also on any of my Yaesu rigs.
Shure makes a mic called the SM-58 excellent for normal speech tones....it is widely used for most meetings and is a excellent choice for a "Podium" mic.
I prefer a "studio" type for the "wider range" as my voice has a lower range and the studio mic's normally will accent these tones better.
The key for me is when someone meets me in-person...They say " You sound in person just like you do on the radio"....then to me that is a good mic and the radio is set correctly.
BUT what works for some, may not work for you....so sometimes your first choice may not be your last.... ( I have maybe 10 or more mic's I keep around) just depends on the rig and the usage...What sounds good on SSB, can be not as good on FM or AM....
Well I am sure this has really been helpful...nada!
All the Best
Gary/W9FNB
I found this link may give you some good info "close to home"
http://www.audiophile.ph/index.php/about