I think you got some info wrong, they would work well out to a 1,000 yards, as I owned one and it was one of the best range finders I ever had! LOL
the main reason they didn;t sell well, was there price, they were over 3 thousand dollars here in the USA< they were BIG very bulky,m had to be mounted super high, and well, they had to be caliber set up for a load/bullet caliber like deal!
and most folks just didn;t think they were worth the money or hassle to have one!

they did however hold the patent on the concept likes, as NO one else was able to make them for a LONG p[period of time and then Burris copied it after it expired at a much lower price tag, about half the price!

so, the main flaw on them was price, second was too large and heavy, and then third , just how high they had to be mounted(I had a custom stock built to get a proper cheek weld on things!
and also, the batterys didn;t last long in very cold weather didn't help any
BUT they were super accurate range finders out pretty darn far, I could get readings on deer at 950+ yrds no problem, something many of my other range finders at the time couldn;t
so, I Guess there not any easier to find over your way than here, I see them pop up for sale here for about $700 bucks USA dollars a=every so often, NOT worth that to me for what I want one for, but some day maybe will find one at a price I can justify again!
Still have the custom stock , it fits rem 700 actions, so, could always be re used again if needed LOL