came across the large size bag which is 70lbs when filled with water for about $60 bucks on craigslist. it retails for about $120ish from what i can see. i'd prefer the xl version which is 100lbs but this seems like a pretty good deal. i have no experience with a heavy bag as what i have right now is a lousy wavemaster. ideally i wanted a 100lb bag if i upgraded but what do u guys think of the 70lb bag, will it suffice or should i hold out for a 100lb bag?