[ocellis]

Once you have access to Spelltrap/Wish, you no longer run out of spells, so the ability to use a longbow is worthless.

If your spellcaster loses hitpoints at all, you are likely in trouble, at any rate, and the additional hitpoints won't make a difference.

I can't think of a reason why one would chose to Dualclass between Mage/Cleric, if the much more powerful multiclass variant is available.

A few Thief levels are nice, though, since it opens up the great Mislead/Backstab combination. Sorcerers still have more high level spells and flexibility, but a thief->mage is hardly a weakling.