I personally don't think twin post lifts are crazy dangerous, but in the context of knowing what you are doing. Yes you can set yourself up for failure by having the truck or vehicle too for forward with respect to the lift points and the truck or vehicle gets out of balance. More of a problem where a truck or vehicle has a large % of weight biased to the rear or front. Obviously the primary problem would be weight on the front with a front engine vehicle. Don't get in a hurry, know your vehicle, test the pivot/lean point when you get the vehicle a few inches off the ground and see what happens, if in question stop and set it back down. *** I was a mechanic back in the late 80's for a few years and had to use an old air powered hydraulic single post lift that would jump the last foot or so when going to max height....talk about scary! This was in a dealership and had the old school large single hydraulic ram in the floor with an x shape setup for the lift points on the vehicle....was scary, I complained....no-one ever did anything about it, the other guys had similar lifts but I was the new guy at the time and got the crap spot.
The best lift is a four post drive on type, where you simply drive on the lift and it lifts the entire vehicle by the tires, and has optional features where there is a sliding lift point or two made on the lift that then you can position to lift the rear or the front of the vehicle or both, to get the tires off (most have a sliding hydraulic type sled thing...thats part of the lift) and clears the vehicle as you drive on the lift but is great to use to lift a fixed point . The down side of this is cost and access under the vehicle depending on what you want to do. Most home users don't have the $$ or space to have a 4 post lift of this type and the utility is limited, depending on what your intended use is, but they are rock solid and basically dumb proof. You can be really limited to access under the vehicle on a 4 post lift but it likely only interferes with certain large jobs depending on the vehicle, that can be worked around, but back to space and cost. If budget and space were not an issue a good 4 post / drive on lift would be the $tuff.
On a twin post lift like pictured up....my opinion is that (when truck lifted by driving forward into the lift), you always set your lift points as far forward under the frame as makes sense on a flat surface of the frame. There is some magic on learning where to position the vehicle relative to the lift, but you'll get that over time. I would extend the front two lift points out and then angle them in to catch the frame flat point as far forward as reasonable, then as to the rear two lift points I would essentially move them in to whatever angle where I could get on a flat portion of the frame. Pick up the truck a few inches off the ground, push it around by hand and see if its "tippy" if so, re-do things. As far forward....means, the lift points are as far forward towards the engine side (front) of the vehicle as you can get them and be under a flat section of the frame.
I don't like the lift points where they are small cylinder post types...these to me are just crazy as some of those have very small surface area on the lift point itself which in my view lend itself to tipping issues, I like the square or block shape, in my view the square of block type gives more surface area and is more stable. If you have the option on your lift points, some have a "C" type shape similar to what a large wrecker uses to grab the front axle on big trucks...those work well.
Take your time, test your lift points and positioning when you get the truck off the ground by a few inches, stop if things don't look right. If the truck is "tippy" and only a few inches off the ground.....its not going to get better when its 5 feet off the ground. Do not let people operate the lift who are not experienced without supervision. Remember that most modern cars are front wheel drive and the weight is biased towards the front. All other vehicles have to be evaluated as to their own dynamics... Mechanical devices do fail, always have a plan on what to do if something falls or breaks and you are in the way (within reason).
Common sense and some experience in a shop environment goes a long way. But as in any shop...things get rushed and things do break. Don't disable or otherwise not maintain safety features. I suspect some people have had trucks fall off jack stands... Be safe and watch the vehicle and test it, before you get if too far off the ground.
Four post lift is the best, but money and space may be a limiting factor.
Its a little hard to fully explain in print, but you want to avoid as best as possible setting the lift (all four lift points) in such a manner as to allow the vehicle to pivot towards the front or whatever the heavy end of the vehicle is. Normally the sides are not a problem, its either biased to far forward or biased to far to the rear. You want a stable lift point as far forward under the heavy end of the vehicle in question. So that the heavy side of the vehicle cannot tip forwards and you want your front two lift points to be parrallel with each other so you dont' have one point on the left front side far back and the righ side front far forward...because once again its a problem with the physics of "things". ** It can be dangerous and take your time doing things.**
