Using absinthe for windows? I've jailbroken before but that was way on my 3G. Just don't want to do banking on it if it's jailbroken and if there's a security hole
as for an average user i would say you would be safe. however, if you ever start messing with SSH then the theory is you need to change your mobile password etc.. for security purposes
i am too paranoid, jailbroken or not, so i do all of my online banking on my PC. probably no safer than doing it on my device but peace of mind helps get me over it