Two quick comments:

1. Higher (whether through flats-to-risers or stem angle) is 'shorter' re. reach, even with the same nominal stem length. Probably a better way to go if current stem is already much under 100mms.

2. For anyone interested, Specialized's 'adjustable' stems > best of both worlds. They work through an internal shim system; once bolted up, very rigid/no creaking etc., and not much of a weight penalty at all. I run them on both my bikes -- the 12 degree version (+8 to 16 degrees or -8 to 16, in 2 degree increments).