"JohnL57"I've had both and still have 2 Marauders.
Here's my $.02 worth.
Discovery-Pros: Light, uses low fill pressure making scuba or hand pump fills easy. Has open sights if you like them, easy to scope.
Inexpensive!
Cons-Fiddly to single load if using a scope, stock trigger isn't great (but can be replaced or modded), possible poi shifts due to weak connection between breech and airtube (there's a teensy screw under the loading area which is the last fastener in the front pat of the breech).
No moderator/shroud, so it's fairly loud in stock form.
Marauder-Pros:
Multi-shot, shrouded barrel makes it quiet, Very solid breech/airtube attachment, very nice trigger! Can be tuned for power or shot count, lots of aftermarket mods available.
Cons-Heavy gun, requires higher fill pressure, no open sights, more expensive than Discovery.
If iron sights and lightweight single shot are what you want go with the Discovery.