Instead of system, I think you mean type (タイプ)?
This basically just expresses what “type of host” he is. For example if it says “Johnny’s-kei” (ジャニーズ系)it means that that hosts appearance or actions are similar to someone from Johnny’s Jr. Some, for example say “Geinin-kei” (芸人系) which means he’s like an entertainer, perhaps funny. “Iyashi-kei” (癒し系) would likely mean that he is good a listening or making a customer feel comfortable or relaxed.
I personally feel that the hosts that I have met recently and in the past are nothing like they describe themselves to be. “Ouji-kei” (王子系), how narcissistic must you be to believe that you are like a prince? Lol
As for EST, every customer will have a different experience and a different opinion. For example, I went to shokai at Club Sexta with one of my followers here on Tumblr. I absolutely loved the place and have since then gone back 3-4 times and now have a tantou there. She, on the other hand didn’t like the place too much. Needless to say, we both didn’t enjoy EST lol. To be honest though, my worst shokai experience had to be EST. It is the only time I have been to a shokai where I was so bored with the hosts they kept rotating over to our table that I had to kept asking them to change. Also, during shokai, do not expect Yuzu or Sara to visit your table during shokai. The only reason Yuzu and J.P. visited our table was because the girl I was with requested to see Yuzu (for me lol). He is after all the daihyou of EST as well as one of the top hosts in Minami but in my opinion extremely narcissistic and kind of made us feel like we were just wasting his time. Though, I will say that he is good eye candy and that is about it. I okuri’d Reo and my follower okuri’d J.P. but we both never plan to go back there.
Aside from EST, I often here that the other clubs in their group like G-TOP and Akatsuki are quite fun. Never been there personally so I can’t really base this information on my own experience.