I was quite sceptical when I first heard about the lane gainer. Having tested it for a while now I cannot but rate it 5 stars. We only have a small pool available at home (as most people do) and I hate commuting to a large pool for the daily swim. The lane gainer is a perfect solution.
I have another conventional leash fixed to the top of a wall with a carabiner at the loose end that I can attach the lane gainer to. This way the product does not disturb the leg work. All in all, I am very happy with it, it’s worth every penny.
Having said that you should consider that the swim experience differs from normal lap swimming. Here are three observations:  1. hips are in a neutral position rather than towards the bottom of the pool (especially if you attach the lane gainer on a higher point to have free space for the legs). 2. Usually, crawl swim forward movement will cause a bow wave with a trough in the water surface near the ears. After turning the head, a breath can be taken in this trough without the need to move the mouth above the average water surface. Now, with the lane gainer the trough is missing so you will have to move your mouth higher up to breathe. 3. Swimming Side-to-side movement is normally kept to a minimum. Usually the leg kick maintains the line of the body. Using the lane gainer you will instantly notice that you tend to drift to the sides. BOTTOM LINE: Get the lane gainer but bear in mind that exclusive use might have detrimental effect on your technique in the real world. By the way: When you first use it tell the folks at the pool what it is about. Otherwise they might think that it is a gibbet :-)

I have been on the road for the past 2 months and this is great when you do not have access to a lap pool or when the local pool hours do not go well with your work hours.  It is very light and can roll up very small and fit in a bag, carry on or suitcase.

I like how it is adjustable so it can work with the length of pool you are dealt with at the hotel.  By adjusting the length, I also find that the tension is also increased (smaller hose = more tension).  

I find it is best to attach the belt to something that is above the water level so when you use it, the hose is not physically between your legs and you aren't kicking it when swimming.

IT ALLOWS ME TO SWIM ENDLESSLY EVEN IF THE  POOL IS FULL OF PEOPLE. . NO TURNS, NO LOOKING OUT FOR OTHER PEOPLE SWIMMING IN YOUR PATH. I CAN JUST ZONE OUT AND SWIM.