Yea you will be able to see the slots cut in the carb when you use the silicone but it will seal better than an o-ring its got to have pressure against it to work ( the o-ring) and if it comes lose your engine will eat it might not hurt but if it snags on a port and breaks a ring your going to be in deep poo. The silicone works for me have not had a single leak and its very easy to use and clean off but I'm not going to try and talk you all out of your favorite way if you want to use an o-ring just letting you know what can happen if they get lose and wreak your bicycle motor then you will not be able to ride your motorized bicycle until its repaired. something to think about.
Or drive you all crazy wondering will it come lose or not.
got you wondering yet?! To check for a leak free seal spay the area with carb cleaner or starting fluid you could use a spray bottle of water if you have to all will change its idle if there is a leak most likely it will die when sprayed and its leaking. do not spray the intake as it will die making you think you have a leak when you don't
Norman