Well, I'll let you decide if the cost is worth 110gr... A SISL2 + SpideRing SL isn't cheap, it's a stunning piece of engineering but it's expensive.
Personally, I'd say that upgrade alone will hardly be felt on the road. Upgrades that are done just for weight savings need to be added up to start making a noticable difference (except maybe tires/tubes/rims). 100gr here, 50gr there, 130gr over there... But then it takes money to make enough small weight savings to make a difference out on the road.
I wouldn't say it's worth it that much on it's own but that's just me. Also, the 3D forged SI you have is a bit stiffer and more bombproof than the SISL2... Not that the SISL2 isn't stiff or durable but you wouldn't be upgrading for anything else than weight. I like to upgrade parts and usually try to save weight in the process, but usually also to improve fit and/or performance... but I must confess, sometimes also to have something different or special, so I can understand the... the 'lust' of sweet high end parts!