Thanks so much, JakobT, G-Dog, and EatS1stBassist,
I should have mentioned that I am married, and I think the $500 Rumble 200 is all I could justify to my wife, especially since my band isn't even gigging at this point. The only way I could entertain the idea of getting a 500 is if I could sell the Peavy Mark IV and cabinet for $700 price of the Rumble 500 (or maybe as low as $500 and supplement the other $200).
I have been researching on Youtube, and many bassists have been making the Rumble 100 work even in outdoor settings. I figured the 200 would be enough, especially if it could be used in tandem with the cabinet, which I would only use in more expansive settings (due of the weight).
Another thing I like about the 200 is the 15" speaker. I thought for reggae it might have a fatter sound than the twin 10", though I'm open to correction on this. I'm not interested in anything at the high end, no interest in Chris Squire/Geddy Lee progressive rock or slapping. But if you guys think a twin 10 can be thick and heavy, let me know.
Thanks for your advice. I wish I were free to spend what I want to. However, since my wife is pushing me to buy a portable air conditioner that I don't need, maybe there's a little room for negotiation...