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Short answer: Yes!
JC gives you the three epic Gems that can grant you a substancial ammount of Agility as is the same with LW with the wrist enchant. Stacking these two professions is a wise decision.
Skinning gives you a Crit increase... one of the worst combat ratings and Mining gives you Health... which does nothing for your damage output!
However, only switch over if you are serious about getting that extra DPS out for raids.... otherwise keep them two professions for making gold.
Hint: if you do decide to switch your professions, farm all the materials you will need with your current gatering professions.... it will save you money... but maybe not time!