Enlarge Spell vs Force of Personality for a Shiradi multiclass sorc?

[DDOisFree]

14 Sorc / 2 Paladin / 4 FVS Bladeforged (Perma first life gear farming and easy caster alt, just grinding ETRs, takes sorcerer at level 1 not paladin)

8 Str, 8 Dex, 16 Con, 14 Int, 8 Wis, 18 Cha starting stats

Feats:

Level 1 - Quicken Spell
Level 3 - Mental Toughness
Level 6 - Improved Mental Toughness
Level 9 - Skill Focus: Spellcraft
Level 12 - Empower Spell
Level 15 - Maximize Spell, Follower of the Lord of Blades
Level 18 - *EITHER* Force of Personality / Enlarge Spell, Grace of Battle

(Level 1-14 Sorcerer, 15-16 Paladin, 17-20 FVS).

The option would be based on whether or not the extra will saves would be noticable in Epic / Reaper content, vs my current pick of Enlarge Spells for massive range Scorching Ray and missile spams.

I previously played as a 2 Pal / 18 Sorc on the first life, and have currently done 1 or 2 ETRs as 16 Sorc / 4 FVS, and came to the realization that my Irresistable Dance rarely works with low spell pen, and I would also have to drop Greater Teleport which is never even used anymore (DBF, Recon and GH are still available to the build and all I need for level 6 + 7 spells, DBF is still crucial for speed when solo farming gear for my Wizard main).