I don't see why not get a JBL, I've been using them for the last 25 yrs (they were distributed by Voit AMF) and esentially is the same gun as today, a couple of improovements, but the same gun in esence.
I don't dive every weekend, but I do my share of diving for sure and I have only replaced bands, tips and a couple of shafts.
Overall is a good gun, comparable to the AB Billers, both brands have a great parts availability, so replacing any broken parts shouldn't present any problems.
the most expensive guns like Riffe, Wong and others, are excellent guns, but they are very expensive to acquire and parts are more expensive than the other brands.
If you plan on spearfishing every weekend, you probably would like to buy the top notch brands, but if you're going to spearfish once in a while, get the economical JBLs or AB Billers, you don't want to have a $500.00+ gun sitting in your garage to be collecting dust most weekends while you do some motocross or any other activities.
And yes, they get the big fish too, I've speared a lot of 20+ lbs fish with my JBL, it's not the gun, it's the fisherman what counts, a friend of mine has a el cheapo type Kmart gun and takes more fish than me every time out.
Practice as much as you can and most of all enjoy your dives.