If you're talking about Downstream I think that's fine, what does your Upstream look like?
What is the power on that?
SNR is best over 30, higher is better but might work well with even as low as 25 at times.
Currently my SNR is the same as yours (downloading is working like a dream) and I'm getting packet loss but that is due to my Upstream having a power level of 57.(They are still trying to fix this issue, been getting the run around since September 27th)
But yeah the problem might be your Upstream.