Farmrboy, if you've never owned a laser before, hunt out YOUR local laser supplier and find out if he fixes them himself or sends them out to be repaired, your wanting a person local to you that sells and FIXES lasers and has equipment on hand at all times. Most any of the major players in lasers today has good equipment they sell and can get parts for. I'm not familiar with the 622 personally, but own the 422 and also the 722 laser, both dual slope, the 722 is my favorite of any laser I've ever owned or used bar none, but that's personal choice.
As for being a piece of junk, that depends on what your definition of junk is, spectra as with many companies make a wide range of lasers quality products, they'll all do the job and measure accurately, the difference being in how long they last, how much trouble they give, how easy they are to get parts for and a host of other things, the single main thing is how well you take care of them and handle them. Do you take it in every night and set it on its shelf in the house or shop or let it bounce around in its box in the back of your pickup for weeks on end, do you put it in the cab and keep it safe, warm and dry when not using it, or let it sit out in the rain and snow for day's on end even when you don't use it, do you handle it like a carton of eggs or toss it around like a shovel has more to do with how durable it is and how long it lasts.
I like the dual grade lasers myself, would never own another single grade laser, as for what one of the two you have listed does over the other, can't tell you for sure, I'd have to study them for a while but the dollars are not large in difference between the two from I can see on the internet, there's a huge jump from those two you named to the 722, as in three or more times the price, so to me, both those you named are lower end lasers just from price alone.
My 422 has its place, but to do it over again I'd have bought another 722 and had two of them, in all the years I've ever owned the 722 its never yet caused me a seconds grief or not worked, the 422 is hard on batteries, has only a 12 volt charge cord, has shorter range than the 722, is much lighter and is much finickier than my 722, doesn't have the adjustment range of the 722 and takes four times longer to self adjust than the 722 and when the wind affects it, which is much more due its lower weight, shuts down to self adjust then starts back up again, meaning I have to spend far more time wondering or waiting if its a wind issue or battery issue with the 422 verses the 722, my 722 only ever shuts off if its battery related, usually dead and needs a vehicle to plug into to keep running and using it, the 422 that's another story altogether and causes its own set of issues on a daily basis which cause me more trips to the laser to check out in one day than the 722 has caused in over a decade of use combined.
My advice is to find the laser fix it guy who's local to you, go and run them firsthand and ask questions to that person and ask for a demo of both, as in you take them home, either new or used units he has on hand and run them for a few days each and decide from there.
All anyone here will give you is an opinion of what they think, some are comparing them to high end lasers like myself, others have little to no experience with any laser, some only use them at work and have no clue what it costs to keep them going, others only pay the bill and have hired guys who run the lasers and don't use them personally and a couple hundred more things tossed into the mix, not to mention a few hundred opinions on different brands of lasers, you need a starting point of the pro's and cons of each laser, and first hand experience is the best way to get that, a local laser guy should be able to help you with that, if he's worth a pinch of salt that is.
Some places offer a rental on lasers, I'd recommend that as well until you have it narrowed down some more on what exactly your needing in a laser.
Buying the stuff is only half the part, keeping it running when you need it is the other half, just yesterday we pissed away three hours on a receiver only to find out the receiver has a problem, so we ended up using a back up receiver and only one when we needed two, so we made due and got the job done, the first of the week the receiver goes in for repairs, same for my 422 laser, it wouldn't start up either yesterday for some reason................again, so I dug out the 722 and had to wait for it to charge so we could use it.
They only cause grief on the cold, windy, snowy day's usually on a weekend, never in the dead of summer during the week, or so it seems to be the case with me anyhow, or else I'd have run the half hour to the fix it guy and swapped out lasers and receivers yesterday afternoon and kept going full tilt instead of being dark and not done and now the frost is too deep again to do finish work, so in essence I've now lost a week or more in time over the laser and receiver issue yesterday alone. To send them in for repairs to somewhere not local to me, I might as well hang out the for sale sign on my door, I'd never get anything done ever waiting for a laser and receiver to get fixed. Best of luck on whatever you decide