I've used the Thomann Monster Reed both in strengths of 2,5 and 3. They were about on par strength wise of Legere Signature synthetic reeds. I used these for about three-four months and concluded the sound and ease of play was not for me after all.
Now don't get me wrong. I think the reed is great for the ~18€ price and if you've heard it and liked the sound. I would give it a shot. But if you can spend a little bit extra for a synthetic reed, I would recommend to go for the Legere Signature reeds over these.