You just make me curious to check this wallet and I don't see anything special there. The first part where you need to log in in their website is a big no for me regarding the security part. It's a web wallet so the security can never be at the top (website can just go down together with your funds). The only appealing thing they have is the multi currency support. In fact is not that much as an organized person can keep different wallets in the same PC without having any trouble. Lastly they have multi sig which should be a true security measure, maybe be it is but still it remains a web wallet which offers multi currency and multi signature.
If that's ok with you then your choice, I would never touch a web wallet no matter how good it may be.
I mostly chose this wallet because of the ability to both read and send omni tokens and couldn't find any alternatives for that. as for "online" , that's what I'm asking , do they keep anything in their sides ? have you used them yourself or just giving an opinion ?
Just giving my opinion, it's from a long time I am out definitely from the web wallets (not online wallets but web wallets).
As for the question do they keep anything in their sides, only they know so I would say it's a gamble to try to keep all of your fortune there, a big one I would say. They may say that the password ,seed or whatever this wallet uses only reaches their servers encrypted but we may never be sure about it.