I bought the 3D reel and I'm very happy with it, but my purchase was more out of necessity due to tennis elbow, golfers elbow and shoulder pains. I either made my day less strenuous, or I pretty much stopped window cleaning.
Along with the 3D reel, I started using an Xtreme pole and brushes, put 30m of Gardiners reinforced pole hose on my main reel (to make it lighter to pull round) and got rid of any jobs that involved awkward stretching over connys etc. I haven't binned them all but I have binned the worst of them. Also I work slightly less hours per day.
I have to say that since I made these changes, my elbows and shoulders are far better and my pain level is reduced considerably.
I'm 59 now and I'm still in good shape.
I would honestly say that when you are younger, try and make your day as easy (and as less strenuous) as possible; buy the best equipment you can and if you think a gadget or gizmo can help take the strain from your body, speed you up, or reduce stress levels, then seriously think about getting it; it's not as if we can't afford it!
Investing in good kit and making your life easier (and less strenuous) when you are younger will help maintain your body in good shape, for when you get older.