I haven't tried the no_note=1 but I would imagine that that is the case. I never had a need to pass customer's message information to Paypal, my main concern was to pass the address to make sure that it is in fact the billing address.
If you change it to "0" then the customer message will pass through to Paypal. There shouldn't be any problems unless that information doesn't get pass through and instead it would just have an empty box for the customer to fill in the message again in Paypal. If you happen to test it out, let me know the results for future references.