I bought and love the entire Groove system!
I bought the entire Ultimate Direction Groove System (AMP, Mono belt, and Stereo belt) in May for my fall marathon's summer training. It gets hot and very humid in Southwestern Pennsylvania, so I opted to go with the Groove system because I thought they'd be cooler than the vests. I bought the entire system for a few reasons--I have a big cell phone, I'm not a fast runner and like the idea of having extra water with me, and a few others. Here's what I've learned about these products after three months of long, medium, and short runs.
Yes, it takes a few runs to get used to to what another reviewer called the "soggy baguette" feeling of a half full bottle. The body bottles are soft and have no structure when they are empty. However, after 3 or 4 runs I really didn't notice a problem. I adjusted to the feel and it's no longer a problem. I like the ability to strap the AMP to my hand with the "X" shaped straps on the back; however, as the bottle is consumed, I find that I don't use the straps and move the bottle from my right to left hand as I go. Whatever is comfortable. Again, I love a handheld and feel strange running outside without one--even take one with me on 5K's! The two pockets on the outside are about the size of a gel pack each and there's a small velcro pocket on the bottom big enough for a few electrolyte capsules. I don't use gels, and since the side pockets don't have closures, I really don't use them for anything. I have put my car key in the side pocket and clipped it to one of the bottle straps for fear of loosing it.
So, for the AMP--I love it.
The MONO Belt:
I bought this belt because I have a Samsung Galaxy Note 5. It's a big phone, but when you add the case, it's even bigger. The description of the Mono says it's iPhone 6 Plus compatible (which is about the same size as my Samsung) so I bought the belt more for carrying my phone than carrying water. It fits great, doesn't bounce and has a small velcro pouch on the right side that holds my car key perfect--I think it's meant for electrolyte capsules. The zippered pocket is moisture proof will hold my phone outside of the phone case. It won't fit with the case on. However, the outside pouch that's meant for the water bottle holds my phone perfect. If there's a slight chance of rain, I put my phone in a zip lock bag ad don't worry about it. The front part of the belt can be swapped out for the front part of the Stereo belt that has pockets and creates a new system. I use the combined system occasionally because my phone does fit in the front pocket of the Stereo and I can carry an extra bottle of water in the Mono portion.
So, the Mono--I love it.
I bought the Stereo with the bottles. My older, rigid UD bottles will fit in the Stereo without a problem, but I liked the idea of the Body Bottles fitting up against me and reducing bounce. The Body Bottles aren't cheap by themselves, and there's a definite cost savings buying the belt with the bottles. The belt fits well and doesn't bounce. My phone fits in the front zipper pocket, albeit a snug fit, but it fits without fear of damaging the belt. The front pouch also has two pouches that would be great for gels or such. I use one for my electrolyte capsules and the other is usually empty. The back portion of the belt holds two body bottles and has a zippered pouch that will hould a fair amount for a belt. I put a 300 ml soft flask with my nutrition in this pouch on my long runs and it fits without a problem. When my hand held is empty, I blow it up with air and swap it out for a full bottle from the Stereo--blowing it up makes it easier to get in and out of the belt. On my really long runs, three bottles aren't enough, so I have to plan having a place to fill up my empties--a water fountain, convenience store, or even circling back to my truck.
So, the Stereo belt--You guessed it.... I love it.
I really can't find anything about the Groove system that I don't like. The bottles do warm up pretty fast (I'm guessing it's because of the thin nature of the bottle and lack of insulation,) but since I only put water in them it hasn't been an issue.
Hope this review helps you in your decision!!!