we do not share your data with anyone and there are many ways to control the visibility and storage life of your data here.
but the internet is a public space and you should always assume your data could be compromised.
be smart with your password, use tor or a vpn, and use pgp for sensitive communications.
Like all security questions this is relative to your idea of risk and the conditions in your jurisdiction. That said an ounce is pretty safe from all perspectives, easily concealed and not worth the time of evil agents.
You can basically put the potential problems into 2 categories: Financial Losses and Freedom Losses.
For financial losses your 1st risk is a bad seller, if things go wrong you will need the escrow system to get your money back. If you are a noob this might take time while you build your reputation and extend settlement time. Otherwise there isn't much risk here.
For losses of your freedom it depends how bad your jurisdiction is but there really aren't many places left on earth where you will be abducted for a small amount of cannabis. Again if you stay with proven sellers the stealth will more than cover this possibility.