No offense but the DR reels are not the greatest by any stretch of the imagination. I have seen more than one come apart on a dive and they both bird nest fairly easily and are hard to clear underwater. If you buy one, you will shortly be buying a better one.
There are two approaches:
1. The "I am going to birdnest it and want it to be easy to clear underwater" approach:
Larry Green Reel
Price runs around $130.
This design is very open, very easy to clear if you develop some backlash in it and it is also very easy to operate due to the side handle design which allows good drag control with thumb or fingers. The adjustment screw alsos allows good drag control as well. Side handle designs are also easier to use in general and are more ammenable to use with a back up light in hand.
In the rare case where you really screw it up, ht eline winds nicely around the frame so it will still get you out of a cave with out excessive mess or entanglement.
2. The "I want it as idiot proof/birdnest proof as possible" approach.
Salvo reels
Price runs about the same as the larry green reel at $130 for a Salvo and maybe $170 if it has an "H" on it.
The Salvo/Halcyon design has very tight tolerances to prevent the line from wrapping around the spool. It can be done but it takes superhuman stupidity to do it. And when that happens, you'll need tools to fix it.
400' is fine for a primary. 150' is common for a safety reel and 50' is common on a jump reel. For very minimal pentration a150' jump reel is not a bad choice and would get you through a cavern course. There are a few (not many) caverns/tunnels where a longer line may be beneficial for tiying into the gold line.
Personally I like a 400' primary, a 50' gap reel and a finger spool with 150' of line for my safety "reel".