Well, I am not the most trusting person in the world.
I don’t like the fact that the site is up without correcting the glaring mistakes in English. I wonder about the integrity of the site and developers.
Do you really want to place all of your information is in one place with one password? They may, at the very least, sell your email address to spammers. At the worst, they can steal sensitive information.
Also, I don’t know how well these developers know about back end security. If they are trustworthy and have integrity, it doesn’t mean that they can’t be hacked
I would suggest using one account and setup forwarding to the main account from the others