Hey Sono! Nice to see you back posting. Both you and mark12_30 demonstrate your keen intelligence (not to mention good taste) once again.
My own exhaustive (some might say exhausting) research on this topic has convinced me beyond a reasonable doubt that Tolkien conceived of Balrogs as winged creatures, at least at the time of the writing of LotR. There is compelling evidence of First Age wingers, too, but I won't rehash arguments I've made of old in the linked threads here.
I will, however, note that the Silm "troll-guard" reference is suspect to say the least. See
this section of my Olog-hai article for a comprehensive investigation -- or just let me sum it up for you: this section of the published Silm was constructed from various source texts by Christopher. Not one of Tolkien's source texts as published or described in HoME refers to trolls, so how they got into Christopher's Frankenstein version is anybody's guess. This instance is also the sole mention of trolls in the entire published Silm as far as I know.
So troll-guard references in relation to the Balrog debate are simply not compelling.