I'm about to buy a new gun and this seems to be a good one for my purpose. Question--
Is it a durable product and I have a devilbiss jga cup gun which has been great. If these siphon guns are so bad compared to a hvlp,,why are they selling for $500.00 or more dollars. I'm making a spray booth now and am sure I'll have a bunch of questions when buying the paint. Working on a 73 cj5 and 36 5 window coupe.
Thanks

The FLG4 is a good mid-value gun from DeVilbiss. It should be as durable as any of the DeVilbiss high end guns. While you won't get quite the level of atomization as a Tekna or ProLite, it is still capable of laying down base and clear very nicely. Make sure you have a compressed air source that can provide at least 13-14 SCFM @40psi though.
The JGA is still sold by DeVilbiss. The suction/pressure feed guns typically see much more usage in fleet painting and vehicle restoration. Remember that the JGA has been around a while and was designed for the older paints. The newer gravity guns are easier to use and clean, so they have gained a lot in popularity over the last 10-15 years.
What are you going to be spraying (paint-wise) on the resto's that you are doing? The JGA may still be a good choice if you are looking to do an older lacquer-type, etc.
HVLP is an EPA/SCAQMD requirement for those painters in designated air quality districts. The goal is to reduce overspray and increase transfer efficiency. However, HVLP doesn't always give the best performance. There are many "trans-tech" or "compliant" caps that do as well or better than HVLP. The choice to use HVLP or not should be determined by evaluating the requirements of your air quality management district.
Hope this helps!

I have a FLG its a good gun, although I use it for primer epoxy feather fill but I am sure it will spray Base coats as well as clears fine.

Nothing wrong with old siphon gun If it works for you use it.