About the length:
I think the Tenga Egg was made to address the length issue. It can stretch as far or as little as a guy needs it to. It's also directly moldable (as shown in the video when the girl repeats after the World Champ as he shows her how to squeeze on or twist the egg while it's around a man's penis). This is a big difference from the Flip-Cup, which appears to depend entirely on two things: (1) vacuum/pressure and (2) the size (length and width both) of the man's erect penis. If a guy's penis is wider than normal, it looks like this is prepared to do the job, but if it's narrower than normal, I'm not so sure. Similarly, if his penis is too long, it may not please him, and if it's too short, then he can't reach the end. The penis appears to need to be in that 6"-give-or-take-an-inch range for the Flip-Cup to work best. Any longer and your head will probably ram into the plastic edge (which could hurt, lol) as you try to bring the Flip-Cup's body towards yours; and any shorter than that and duh you won't reach the end.
The problem with the egg, of course, is that it's a uniform polymer shaped like a shot glass whereas the Flip-Cup had all of those different-feeling ridges at different points along the way. So it sounds to me like if you're a man with a long-enough and wide-enough penis that the Flip-Cup would be preferred, whereas if you're a man with too short or too narrow of a penis that you're forced to settle for 2nd best which is the Tenga Egg.
Then again ... some of those male Western porn stars probably are too long and too wide for even the Flip-Cup, meaning they'd have to settle for the super-elastic egg as well.
===========================
About the reuse:
I think it's half and half, Rein. Just like with men's electric shavers! The company tells you to replace the blades once every two to six months. Yeah right! Most men wait a year or two before they replace the blades in their electric shavers. Why replace what still works? Why spend all that money for 10% improvement? Why not wait until you'll get 20%, 30%, 50% improvement?
But just like shavers, the company isn't lying completely: the blades do get dull eventually and do need to be replaced. This sort of planned obsolescence is what you'd expect to find in a masturbation toy, and so it's no surprise that Tenga's invented a polymer which does the following:
(a) feels good
(b) isn't known to cause cancer or other diseases
(c) only lasts 50 "normal uses"
What's a "normal use"? This to me suggests that the gel is gradually ruined by plain old water: it chemically degrades with repeat use. It's not physically degrading (e.g. tearing, eroding due to friction). The lube should minimize that. It's got to be due to the water (a) in semen [if you refused to expose it to tapwater] and (b) from when you wash it. I'm guessing that it probably lasts 50 uses if you wash and dry it as directed, < 30 uses if you wash it but don't promptly dry it as directed, and around 60 or so uses if you open it up and wipe out the ejaculate with a dry tissue or something. (Which I don't recommend, but I'm just imagining how you could minimize exposure of water to the gel.) I wouldn't be surprised if the gel-foam's chemical degradation is helped along by the lube they sell you. So maybe if you were to wear a condom and place the lubricant between your penis and the condom itself, you could make the Flip-Cup last longer ... except good luck getting the condom to stay on!! XD If the vacuum doesn't tug it off of you, the lube you put between your dick and the condom definitely will help it to slide right off the first time you pull out! lol
This is probably the same reason the eggs are considered one-use only products: I bet they turn into mush when they are exposed to running tapwater. Or maybe they harden. The possibilities are endless. Having never used one or seen one in real life, I don't know, but I'm guessing it's got to be chemical degradation as per planned obsolescence. You force the consumer to buy more eggs when the eggs don't last forever.
That's the damn thing, though: if you're a guy who masturbates anywhere from four times a week upward, the Tenga Flip-Hole just isn't economical at all! :\ $100 for 50 uses? That adds up way too quickly. Sure, $2 may sound nice when you consider how expensive a call-girl is by comparison, but she's a human being with breasts and buttocks and warmth and noise and everything: and this is just you all alone with your dick in a box ... err, plastic tube. ;p