The M3 is a beast! Great quality, easiest piece of equipment to put together I've ever bought, and gives a super fun, intense, efficient, full body workout (if you buy the v-strap, tow rope, power tether, and the strap harness, and use the wheelbarrow position as well as the sled position - all worth it!).
I was looking for something that would give me a full-body workout in 10-20 minutes with minimal time and energy taken up changing up settings and attachments. This is definitely that. I already had the Relentless Rope, which is the one piece of equipment I have that is so quick and frictionless to use that I use it every day. The M3 has the same kind of build and simplicity of design. I'm busy with a lot in my days, and I'm over 50 with less energy overall. Having something that I can literally just grab and go for a workout to stay in shape is important.
Well worth the purchase. It is very heavy and is definitely an intense workout, which I love, but it's not for someone who would not want some heavy lifting and intense pushing and pulling.
I've seen reviews of the M1 where the reviewer wishes there were a level 4. I do feel that way about the M3. Yes, if you go faster the resistance increases, but I don't want every workout to be about speed. I want the option to go slow and push and pull more weight, so a level 4 would be great. That said, level 3 still offers an intense level of workout. I haven't added weight plates onto the weight horns either. My understanding, at least for the M1, is that adding weights is for stability rather than resistance. But the M3 is super stable, so I'm thinking with it adding weight would maybe result in more resistance, but I don't know. I'm on a hill, and I push and pull it up the hill if I want more resistance, and that definitely does the trick.
Anyway, great design, as well as great customer service and quick delivery time. Can't recommend the M3 enough!