Limit 2 BTC for unverified accounts is very reasonable.
Reasonable? It's insanely high. In current market that equates to an amount of +$18,000 that you can withdraw on a daily basis, which is something I can't see them continue endlessly. I have a basic verified account on Bittrex, and they lowered my daily withdrawal limit to 0.4 BTC! Unverified accounts at Bittrex can't even withdraw anything, which is quite funny and weird. If you can't withdraw anything as unverified user, why would you be able to deposit? It doesn't make any sense. It's something more exchanges do, and I find it quite shady, especially because of the fact that you as exchange are almost knowingly setting up a noob trap. Once people make the mistake to deposit, they will either leave their funds there for ever, or they will have to get themselves verified to get their coins back.