I would think for a VERY long time before taking a level of Bard. You will see throughout these forums my endless arguments for multi-classing almost every possible build but IMO this is the one and only singular exception. The loss of the extra spells (already tight) is brutal and giving up that point of hard earned (very expensive) Spell Penetration really is a big deal. If the ONLY reason is to get suffucient UMD - I assure you there are other ways including:By taking a Bard level I miss out on my L8 spell and one L6 spell. That means dropping Cone of Cold or Chain Lightning. I think I'd need to experiment with them both after resetting enhancements to see which did better damage.
Ranks: 9
Feats: 3
Luck: 2
Charisma: 14
Greensteel: 6
Titan Gloves: 5
Greater Heroism: 4
From which you need 39 (not 40 or 44 since 39+1=40 = heal scroll success).
You also need to address gear including Exceptional CHA, Spell Pen, and Focus. Consider carefully that there are Greater Spell Pen Items/Weapons available (but not for all spells) and Greater Focus (but not for all schools). The combination of GSP/GF from gear (+1/+1 over SP/F) should be considered in this re-work (but both or either may not be possible).