I've got a Bushmaster dissapator.  If I had a couple hundred bucks would I be better off getting a good scope to mount  on the carryhandle (ACOG, Eotech, or some kind of tradional scope mounted to a  BMAS "wide-veiw"))or spend my money getting an over the handguard mount like a Bennie Cooley or ARMS so I could do the co-witness thing with a cheaper scope like a Tasco?  I've seen cheaper mounts than the Cooley or ARMS, but question their quality.  Any suggestion or other options would be appreciated.  I'd like to keep it as versatile as possible with most shooting being done between 20 and 200 yrds.  Finally, does the height of  a carry handle mounted scope cause any really signifigant issues with the gun's "zero"?  I always hear people talking about the benifits of keeping the scope mounted as low the bore as possible.  Thanks.