I think they're comparable in power (at least with low class Saiyans). Raditz was exceptionally weak compared to Nappa and Vegeta so Raditz might lose to a Namekian of average strength. We see 3 Warrior Namekian's fight Frieza's forces with powers of 3,000 each. I believe they were a bit stronger than the average Namekian, but still.
If Nappa is a super Elite and 2nd to nothing but Royalty, with an estimated PL of 7,500 (or 4,000 if you go by other sources), then the average Saiyan I can see being around the average Namekian, which I'd estimate would be 1,500 to 2,000.