There is confusion about 300D flash exposure compensation and it's very likely 300D does not have it, and unless you use a 550EX flash which has the compensation on the flash itself, there is no way you can compensate flash. I got a 420EX so that could be potentially a problem. Different people have different views on E-TTL metering, but my own experience with G2/420EX shows that the metering can be off quite a bit.
Another point is about build (metal vs. plastic). Not a big deal for most of us, but then, I also realized my EOS 50 (Elan II) still looks like new even after > 7 years. Metal body do last longer.
My 2 cents ...