What are you planning to solo? Ig-Alima?
For most content pre-existing content, the Attack/Defense changes changed very little. saevel already explained why.
The enmity changes do have an effect on solo/lowman. BST, SMN, DRG, and PUP are the jobs that are effected by solo. All I can say is learn to adapt. Enmity+/- still exists. Provoke and similar abilities are relatively (compared to damage) better than they used to be. Use them.