Are you going to make good use of Logitech's software? If yes, then get it anyway. You can get #8 o-rings cheaply enough, and a key puller, if they aren't present, and you want them. However, with a Blue switch, they will not dampen the sound much. Blues make noise when you activate the key, regardless of whether or not you bottom out the key.
If you won't use their software, and it's made like the current Brown version, IMO, choose something else, like from Cooler Master, Ducky, KBT, Das, etc.. Unless you use the software with combined KB/mouse/G13/etc. profiles, they are not priced well for what they are, IMO.
<- G710+ owner