I dont think theres really anything wrong with having metal armor. Ive never seen it person, but I know makers have made them from either aluminum or I think 18 guage steel, that I may be wrong about. Other things is that they may sometimes sacrifice details, for the materials its made of. Dont get me wrong, Ive seen some great looking armor made from metal, such as wickedbeard's Jango armor. Another thing may be weight, but that goes back to what metal and what thickness the armor is. I personally wouldnt mind haveing a set of metal armor, it makes it that much more realistic in my opinion.
I used to have metal Jango armor and yes there where pros and cons. Con, Jango's sholder bells did not lay flat, the weight made them do that. Would have been great for Boba. Pro, the looks very cool and the sound of my MR Jango blaster when I hit it sounded great. Con, trimming it down was hard to do. The guy who made mine was over 6 ft tall. I am 5ft 7in. So, I could not trim it down to fit me. Hope that helps.
I made my own metal armor and the only con I've found so far is it gets really cold in the winter. Once I get my vest I'll see how everything lays on it. Cutting and shaping/forming weren't really a problem for me, I did go through quite a few jigsaw blades but I cut out four sets.
The main pro for me was not haveing to make it look like it was damaged, after I painted it I did everything to it; droped it, beat on it with chains, scratched paint off, hit it with hammers, threw it across the concrete floor at work...the works.
Metal absorbs heat very well. Being a desert person, metal may not be the best choice. Wickedbeard's armour may be a different story though, since it is very thin sheet metal, which I have seen and have trooped next to.