Hi Guys - sorry for the late reply on this Amr
The 5210 and 5215 are pretty similar in terms of balance and not too far different in the butt strength. The main difference is at the tip end where the 5210 is a fair bit softer. I don't have one in my hot little hands at the moment, but I would suggest (like Scott, Chris and Amr have said) the 5210 and 5215 will both work best with the 20K size reel. If you are looking for something to balance an 8000-10000 size reel, then a rod a touch lighter would do the trick nicely.
For fishing the shallows, the 5210 will come into its own for stopping big beasts in tiger country like GT, Dogtooth and monster seriolas, but it will probably be a bit heavy for all day jigging for more regular size critters.
cheers
Duncan