I don't want to encourage any less caution about that lab tested data either.
I had a back and forth with fellow over at the Firing Line who had a Handy Rifle in .243 Win. As he got to within a grain of Speer's lab tested maximum, he was surprised to find his action popping open with every shot, despite checking the latch mechanism for cleanliness and burrs, and his velocity was 200 fps higher than the manual despite his having matching barrel length. He called Speer, and they simply said they stood by their data as being accurate.
One thing the QL program will do, if you have correct powder energy content and burn rate and some familiarity with their workings, is determine what pressure you need to get a certain velocity extracted from that charge weight's energy content and its burn rate. Burn rate can be adjusted by chronograph feedback from lower charge weight loads in your gun (and often needs to be), and after doing that for this fellow I figured he was at something close to 77,000 psi. Basically proof load pressure.
In this instance, QuickLOAD's first estimate of velocity agreed much better with what he was getting than the Speer lab data did.
I had an interesting exchange with a Hodgdon tech about some data that looked out of line in their online data about 231 in .38 Special 148 grain wadcutters and that disagreed with Winchester's original data as well as data friends of mine used to employ. The bottom line was that he had test records and the loads they posted were signed off on by their tech. All he could say was to keep in mind that this is one set of tests fired with one powder lot combined with one set of other components fired in one test gun operated operated by one technician. So it may not apply to what happens in your particular gun. True enough.
So, take caution with all load information, regardless of the source. There is a lot of information on line about how to tweak QuickLOAD to get it to better track your gun's behavior with a powder at lower loads. Chris Long's write-up
is one example. I recommend you use some starting loads to do this to eliminate outliers. Note that the introductory information in the program manual warns you never to exceed manual loads even if the program says it's OK. There are other more specific warnings. I think the long standing advice to check at least three sources of load information (programs included) and start working up from the lowest starting load recommendation among them is still valid. Learn to read all pressure signs
(that would have helped the guy with the .243, as it turned out). If you can afford a Pressure Trace to double check, so much the better.