Well, I've had plenty of Leupolds, and used them.
They are pretty good scopes, but I had problems.
On my 6.5-20x 40mm obj Leupold Vari-X III, I used that on my Winslow Plainsmaster .225 Win. varmint rifle, which doesn't have much of a kick. The reticle came loose and fell down inside the scope. So much for ruggedness. Oh sure, I sent it back to Leupold and they fixed it for free, which was very good service. But I never had such a problem with any of my Springfields. I've also had some of the Vari-X II, the M series, and had some Nikons, Burris, Kahles, Zeiss, Swarovski, Springfield, and my current Unertl 20x Target.
Also, on the part about seeing the difference at 300 yds, my use for these scopes was primarily in 600 yd prone competition, so I saw plenty of what it does past 300. I even beat out numerous competitors who were using Leupold scopes and others, so I don't think it hindered me any to use the Springfield.
For my M1A rifles, which is what these Springfields were used on, the BDC was perfect out to 600, and never even needed one click of adjustment to put me in the X-ring at 600, with a 200 yd. zero, and using Fed 308M Gold Medal Match ammo. I also used one on my Rem 700 VS 308, and it worked great on that too. I tuned my 168 SMK handloads to 2600fps at the muzzle, and it kept the BDC on target.
I'm not claiming that the Springfield has perfect glass, but it is okay. I'm just saying that in my experience, the Leupold is overpriced and overrated. It is okay, but so are alot of other scopes. I had an old Burris that was way better optically than any of the Leupolds I've used. And that broken reticle cured me of thinking that Leupold is "bulletproof".
My current Unertl is head and shoulders over all of them. I love the external adjusting system. The optics are superior. The 20x I have works beautifully for my 1000yd benchrest work that I do now. On a good day, I achieved a 9" group of 20 consecutive shots(in 30 minutes) at 1000 yds with my custom-built 300H&H Magnum, 28.5 Douglas Air-gauged Heavy barrel, with 77gr H-1000 powder behind a 190gr Berger Match bullet, for 2930fps avg. muzzle velocity. Of course my Unertl 20x Target scope was on it, and required 108 clicks up from 100yd zero. At 100yds, that gun can put 5 shots into 1/3 of an inch. At 1000 yds, even on a "still" day, wind will always play some factor.
I have seen some Springfields where the bubble level was off, but my 3 were good. Also I bought all of mine back in 1994, so I don't know if quality has dropped since then. I didn't have an adjustable objective, or illuminated reticle, so I don't know about those models. I always center my eye behind the scope by habit, so I don't worry about parallax issues. The illuminated model wasn't available when I bought my scopes.