The m69 is 10oz heavier and has a 2" shorter barrel. Very different gun. I've played with both and the m69 is nicer to shoot for sure, but the extra half pound on your hip is noticeable. The 329 is fine with full power loads; just not +p. Hsm 305gr bear loads or buffalo bore "low recoil" 255gr hard cast are both heavy but manageable and still carry plenty of energy.
The m69 comes in two different barrel lengths, 2.75" and 4.25". Comparing apples to apples, the 329PD 4.13" is 25.3oz and the m69 4.25" is 37.4oz so there is a definite weight difference. I owned a model 69 for a minute (courtesy of CBinNH), great pistol, I just struggled to shoot it accurately as a hunting gun for deer so I sold it on. I kind of regret that move, I loved the size, feel, and weight of it (not too light, not too heavy). If the 329PD is anything like the Scandium 340PD .357mag I have learned that there is such a thing as too much of a good thing (that being super light weight). I have shot a 460XVR and a 500XVR, but that little Scandium 357 mouse gun is the most painful pistol I have EVER shot.