Emperus :
The DeathAdder also does not feature on the fly dpi sensitivity changing options like most of the Logitech's.. Also, the build quality, for that matter of any Razer product, is always inferior to the Logitech build quality..
The deathadder might not have a button on the mouse for changing dpi, but it does have the program with room for multiple configurations. Anyway - i've never come into a situation where I "just had to" swap dpi to win. Changing dpi that often is more of a hindrence.
As for build quality: They seem to be on par with logitech's wired offerings.
My last few mice were logitech high-end models and this mouse feels at least equal [if not more comfortable] and in the few months i've owned it has given me no grief.
--------
Keep in mind that we are offering opinions here: there is no right or wrong. Just because you are a fan of logitech doesnt mean they are the do-all end-all solution.
Both solutions work: it comes down to what fits your hand and what configuration options you really need. If you want to get technical even a free-with-purchase dell mouse could be used to game with - though, who would want to...