When it came to pure CPU performance there was little difference between the E4300 and E6300 at their default operating frequencies.
The E6300 has just a 60MHz advantage here, so the gains are going to be very minimal. Once both processors were maxed out on our setup using air-cooling, there was just 30MHz favoring the E6300. Again this meant at 3.47GHz and 3.50GHz there was very little separating these processors. More importantly both of these budget orientated processors were faster than the flagship Core 2 Duo (E6700) when taken to the max.