Yup, paypal do not like pre-orders, as it bears similarities to scams.
The gcw zero console used paypal for pre-orders intially. Paypal froze the account and the money was tied up for a very long time.
Michael Mrozeck' the creator of the soon to be released 'Pyra console plans to do either pre-orders or crowdfunding. I'm not sure which method of pre-orders he might use but he lives in Germany and is subject to German laws.
As far as I know its similar situation with google wallet. They may freeze your account.