You still might see an improvement. I only need a docsis 2.0 as well, but when my last one went out, I went ahead and upgraded to this even though it was more than I needed. My plan is only rated at 20 mbps, but yet my average speed is around 40 mbps, and I've hit all the way up to 60 mbps with this.
What service are you on? They apparently do not know how to rate limit your bandwidth! More power to you!