I've laid off of responding to this one for some time. It's technology, and one that can be helpful.
But...let me offer another perspective for you to consider...
While some veterinarians may or may not be great at pregnancy diagnosis by palpation, and others may be too busy for you to get them out to preg-check one cow here and there, a good veterinarian can offer you a whole lot more than "She's open, she's bred."
They may be able to pick up on, and point out to you potential problems that you may not have noticed - or, in some cases, may not want to notice - bad udder/teat anatomy, early cancer eye, cows with lymphosarcoma or reproductive tract abnormalities, cows with no teeth in poor body condition that may not make it through the winter, issues with feed/mineral program, etc.
What if you get your results back from BioPryn, and you've got 40%(or more) opens? BioPryn can't tell you anything but pregnant/not pregnant - and if you call your veterinarian and say, "Doc, I bled my cows and sent the blood off for that BioPryn test, and 40% of 'em are not bred. Whaddya reckon is the problem?"
Well, he/she likely won't have a clue - but, if they'd 'been on your place', they might be able to point out that bull with the hard, atrophic testicles, or know that you were trying to get cows bred during a 100+ degree heat wave, or that your 1st calf heifers are BCS 2-3 at the beginning of the breeding season; that sort of thing.
Yeah, it may be less expensive, up front, for you to learn to draw blood samples and send 'em to the laboratory that runs the pregnancy test, but in some cases it may not be advantageous in the long run.
I believe AlaCowman stated it in another discussion thread, and there's a lot of truth to it...Cattlemen will starve a good veterinarian out of business - and then complain about not having one available when they 'need' one. I'd recommend that you need to let your good veterinarian have some of the 'gravy' work if you want them to be around to help you out of a trainwreck.
I'll be willing to bet that the BioPryn folks won't come out at midnight to deliver that problem calf from that heifer, replace that uterine prolapse - or provide any meaningful insight into why your cows aren't pregnant.
I'm no longer in active practice; BioPryn doesn't impact my personal bottom line, but I know the value that a good veterinarian can bring to the table, and some folks are missing opportunities for enhanced productivity and profit by looking strictly at the cost of pregnancy diagnosis.