Fiona actually didn't have Tears or Spirit. Whenever I solo'd, it was mainly just smashing stuff (and then spamming Pieces once I got to the boss XD)
Taking Pieces, Tears, AND Spirit severely hampers your healing ability, alas (although once Fiona is transferred, I'll be switching out Bravery for Spirit. As much as I love Bravery, I'm not keen on spending skill points and reagents just so I can screw over allied Siegs, Tias, and Eirs whenever they want to use Magic Defense, Hide, or Light Shield)
Honestly, in my experience, the best thing about soloing with a healer is either not needing to rely on potion cooldown in between rooms, or for extended boss slugfest endurance matches. Tia is actually better for soloing if neither of those two conditions arise (IE, meats and apples appear in the stage and the boss is more about pin-point dodge-or-die rather than long drawn out conflicts). Granted, that does depend in large part on your own ability to avoid damage. To even have a PRAYER of victory, you probably need to be a healer if you're inexperienced. But when you are experienced and don't need healing as much, it's better to solo as someone else.
Currently I'm main-ing two full-time fisher-girls. They fish. A lot.