I tried different reports and as far as I can see, the leading 0 works fine, even with the default setting of $accounts_alpha = 0. Not that I checked the code, but it seems like that setting is only affecting validation when entering new accounts / editing accounts?
In addition I would expect a problem like the one apmuthu described to appear when the account code is (by mistake) cast to integer - I don't know if there is a CoA with alphanumeric accounts, but in that case such a cast would fail anyways.
I will give it a try and propose myself as guinea pig - even though as far as I can see the only account in use by me is 0800 and that's equity capital, so not changing frequently.