Decide which features you need. I personally use very few of the features on my FoxPro.
A hundred sounds, not needed, I have ten presets on my callers, and haven't used any other than those since I got my callers. I have a CS-24 that I got to replace my very heavy Minaska Big Country(Really a better caller but big) and I won a Crossfire that I use as a backup to the CS-24 both have the same remote with the same ten sounds on the Pre-sets. I could get away with a Spitfire or Patriot. The CS-24 was used and the Crossfire was free. I use a Minaska M-1 Bandit a lot of the time.
Foxbang, has been a pain. I've had the remote drop on the ground and trip the foxbang, rifle barrel hit it, shooting sticks slip and hit the remote, I just shut it off.
So it comes down to what do YOU need on a caller. No sense paying for something you don't need.
I always suggest that someone that is getting their first caller with a remote to buy the least expensive of a name brand. When you have enough experience to know what features you need you can pretty much recoup your investment and then spend more.
When you say Old Johnny Stewart I think 512, maybe old is a lot newer to you.