200 is not enough to do anything. A more reasonable minimum to send to a new account would be 350.1 XRP.
Well, you are seemingly right. 400 XRP should be enough quickstartie
I'd recommend using any multiple of 50 that is >=300
plus 0.1 or 1 or something small. The reason is that transactions cost 0.000010 XRP so if you give 400 then the first thing the new account holder does drops them to 399.999990 and the last 49.999990 of that can't be reserved for trust lines or trade offers.
Also, giving a fraction extra avoids the common misunderstand of new users: when they see truncated balance summary go from 400 to 399 they think the transaction cost them 1 XRP instead of 0.0000010 (with 400.1 or 350.1 they wouldn't see the balance summary change).