Marauder models -
Used to be only one model in 3 calibers. Now, there are several. The base model is unregulated and uses a Crosman barrel. Nothing wrong with those barrels today, early models had problems, like 10 years ago.
The base model is unregulated, but the hammer spring, preload and transfer port are all adjustable so you can tune it up or down, whatever you want. Mine is about 22 fpe, throwing a 18 grain JSB .22 at about 840fps. It likes 15 grain JSB's as well at about 880 or 890 fps. Very consistent these days as I added a regulator.
Field and Target is a regulated version, non-adjustable and specific to lower powered Field Target shooting. High shot count, but lower power.
Regulated version is new. Don't know much about it. Probably related to the F&T. Comes in both Lothar Walther barrel and Crosman Barrel. Your choice. Lothar Walther is renowned for quality and accuracy.
Semi-automatic version is brand new and doesn't have much of a track record. It's intriguing, but expensive for my tastes for a Marauder.
The rest are variations on a theme. Different stocks, different calibers, lothar walther barrels vs Crosman barrels, etc.
The $640 price tag isn't really considered entry level anymore, that's more in the Avenger / Gauntlet range of $300. Just by being a good solid choice its evolved into a mid-level gun.
Marauder is an excellent gun, but I don't think it's entry level any more. One step up. Good trigger, well tested design, and the rest. I do plan on buying an Avenger when they've proven out, but for now, the Marauder is a good gun