TubeNet

Looking on their website, there is no real description of the shape of the cup of the LM-5. Does anyone have any experience with this? Also, the descriptions for the LM-3 and LM-6 are a bit hard for me to get any kind of mental picture from. Again, any first-hand experience out there? Positive/negative impressions? Comparisons to other mouthpieces?

Thanks so much, tubenetters, for your help.