Different mileage for different folks I guess...Ive had no problems since its purchase in 2011....in fact, bought another for my wife in 2012 and no issues....Why would you buy two more after your initial problem(s)..?
Glad you asked!
1st was a 2-pc travel setup that was a gift. This was the Aluminum with the 6" bucket. On the very first push (dig in wet sand), the shaft and support bent.
2nd was a replacement. The welds on the back of the bucket busted.
3rd was a 5" aluminum with 1-pc handle that came free with a machine. The handle bent and the welds ripped where the handle mated to the bucket. Beer was cheaper than shipping, so a local guy rewelded it and with extra bracing. No more issues. It worked like a charm and I passed it on to another guy just starting in the hobby.
4th was another small basket aluminum with 1-pc handle that was included with the purchase of a machine. First dig the back of the basket caved (flexed) 0.31". The dealer argued that wasn't a defect and was misuse. I simply asked where was I supposed to push with my foot then?
Seeing the arguement was not going to support the customer ... and having already met a guy that works for beer, I saved time and bought a few more rounds.
One might argue the root cause is technique or the operator, but meanwhile, my Stealth scoop has run without any issues. I've also bought and sold several other scoops (Nutall, Trex, StavR) that never had an issue. Heck, I bought one of those cheap Ukranian eBay scoops that are known for poor welds and managed to make it work without any issues.
So Quality control aside, I think users of both scoops will agree that RTG or equivalent style scoops do not have the same sieve capacity (sq-in of holes or voids) to sift as well as others. Perhaps most notably when in dry or wet sand where water isn't available to assist in deluging the contents.
Another design flaw or perhaps evolution of scoops is the design for the rear of the basket. Newer models are angled and promote pushing, whereas the RTG is flat. The flat or 90° angle makes it easier for your foot to slip off and/or lose force during your push.
Finally, the sheer basket size is a factor for some hunting styles. A 5-6" wide basket is tiny. Many beach hunters are using 15-17" coils. If the target isn't directly under the center of the coil, it just takes too many scoops to recover.