I'm posting this to let everyone interested in upgrading their vaio know that I succesfully upgraded the cpu of the VPCEB1J1E with HM55 chipset and BIOS version R0300Y8. I upgraded from a i3-330m (G1 socket, C2 stepping) to a i5-560m (same socket, K0 stepping) and notice a considerable boost in overall speed and response.
Planning to do a upgrade on the VPCEH aswel, from i3-2330m to i5-2540m, will post the result.