multiclass feat selection

[Raiken]

currently im a 2/1 fighter/sorc omw to 4/10.

so my question is should i invest some feats/enh is spell penetration to make me as closely comparable to a full sorc as possible? i also plan on the heightening spell to make up for some points on my dcs for some spells.

any other suggestions would be appreciated as well.

thks

[Raiken]

forgot to mention, currently my feats are : dodge, toughness, mobility, and spell penetration