Hi Sanjeeb,
I'm kind of in the same situation as you. I want to wall mount my R-51M speakers and asked for help from the community. (See Wall Mounting R-51M Speakers? last entry 1/2/19) Like me, you seem to have researched as many wall mounting brackets as I did, and came up with the same options. Here's what I did and why. I went with https://www.amazon.com/VideoSecu-Clamping-Bookshelf-Surrounding-MS56B/dp/B000X9O8SI/ref=lp_297859_1_9?s=electronics&ie=UTF8&qid=1546793207&sr=1-9 For several reason's to include almost 1300 reviews of the mounts and decent rating, solid construction, ability to clamp, screw, and strap the speaker to the mount, and lastly, it has a minimum width of 5.3", swivel 360 degs. tilt up to 10 degs, and hold up to 33 lbs (My 51s are 11lbs a piece) The other two mounting brackets hold up 55 and 66 lbs respectively. Which I felt was overkill. And for one reason or another, I didn't feel they fit my needs.
I just got them delivered yesterday and have yet to mount them on my wall or even to open the box. With that said, I'll probably mount them on the wall over the weekend (with any luck) after first determining how to attach the speakers to the mount. I have a few ideas and I hope to channel my MacGyver creativity into a workable solution. BTW....nothing I'm considering has to do with using screws to attach the speakers to the mount. That's crazy! If you've come up with a solution since you posted this, I'd be interested in finding out how you did it. Otherwise, stay tuned