A casters +5

[Desteplo]

Is it worth stacking dragon sorcerer and evocation wizard + 5? A+10 and sorcery points seems good
-or even clerics +5

[djreynolds]

I've seen sorcerer/wizard and sorcerer/cleric.... its not bad.

Even just grabbing sculpt spell from evocation wizard and then going sorcerer is okay.

[TheUser]

Needing 20 cha and int as well as 6 splash levels of sorc is a steep cost. My preference is 5-6 sorcerer levels (for 3rd level spells and fire damage boost followed by 2 levels in invoker (evocation wizard) since their best feature is @ level 2

[Drackolus]

I would say almost certainly not. Higher level spells are too good (dimension door, mass suggestion, etc). And if you are doing point buy (and even if you aren't), you will have to completely gouge your dex and/or con.
I would definitely pick one or the other.

Not to mention that you'll never likely get the payoff, as the level is super high anyway.