Another I need help with a purchase decision

Recently someone has stolen my monopod (Manfrotto 680) which worked well for my usage. Weight was never an issue for me I used it more then my tripod (Manfrotto 055MF-4 - carbon fiber) which I am also very happy with.

With that being said I do lust for a Really Right Stuff tripod I have the ball head (BH-55) with the quick release clamp. I need to replace my monopod I could get another one for about $70 (Manfrotto 680B) or $150 (Manfrotto 694CX - carbon fiber) this doesn't include the price of a replacement head.

I understand the need of getting the best tripod you can afford but what about monopods? Is the a significant different besides weight and/or price?

What are your thoughts?
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JM