Hi Siddh, Albert is right on the money. I find many clamps suck and damp the life out of the LP. SOmetimes playing without a clamp sounds better. Try lightly tightening the clamp instead on screwing ot right down and the sound changes. Do not over tighten your clamp. It's just there to break up the resonance.
I have used the clamps you are interested in. Firstly, I consider these among the top performing clamps out there money aside. The Harmonix TU-812 mk2, the Shun Mook and the HRS analog disc. I had all three. Sold the Harmonix and kept the other 2.
All three sound different. The shun mook clamp does something to the music I like. Makes the music have more life in it's presentation. It also brings out the harmonics and decay often missing from the recordings. The Harmonix TU-812 has a heavier overall sound. Sometimes muddy and can be closed in. The HRS is the best value for the $. Nice and open soundstage and the highs are very extended. IMO, it easilly beats out the Harmonix for a fraction of the price.
There are a couple more clamps that I have not tried and are supposed to be good. They are the Callas ebony clamp and the Basis clamp.
Well, I don't have a Walker but do have the clamps. Hope the info helps.