How bad are wild surges?

[temnix]

I have a notion to make it so that all spells cast by wild mages are going to be accompanied by wild surges. This is only going to be appropriate, though, if surges allow the intended spell effects to go through most of the time, even if adjusted up or down in level and so on. I'm not so worried about getting gems or fireballs on occasion, but surges disrupting the spells, that matters to me. So how bad, or how good, are they? I haven't played with Neera for long enough to form an idea, or with a wild mage of my own.

[Caedwyr]

Here's a list of the Wild Surge effects. 

https://baldursgate.fandom.com/wiki/Wild_Surge

The in-game effects may vary slightly, but the yellow ones are the ones that are of particular notice.  If some of those surges happen, it's going to mean a reload.  I would think of guaranteed surges being like playing with a critical hit deck or critical fumble deck.  It's going to be something that some people like, but others find way too disruptive.

For quick reference, here's some of the bad effects:

1. Caster suffers a -2 penalty to casting time and weapon speed factor for 1 turn
2. The effects of the desired spell are applied to all creatures in a 15-foot radius centred on caster. Only one tick from a Cloud spell gets applied, one arrow from a Flame Arrow, ...
3. Slow effect to all in a 15-foot radius centred on Point, for 1 turn
4. For 70s, target is affected by:
   1. Polymorph Spirit Wolf: 100% resistance to Cold and Electricity 
   2. Create weapon: Magical +1, 4 APR, Normal Haste, spellcasting disabled
5. Caster affected by Hold Creature for 70s
6. 80% of party gold is destroyed
7. The desired spell is cast twice:
   1. On target,
   2. On caster, where it affects all creatures in the potential AoE.
8. Caster suffers from 100% spellcasting failure and -4 penalty to THAC0 for 1 turn. Innate abilities can still be used.
9. The desired spell is cast but on caster, and all creatures are affected within the potential AoE
10. For 70s, caster is affected by:
    1. Polymorph Spirit Wolf: 100% resistance to Cold and Electricity
    2. Create weapon: Magical +1, 4 APR, Normal Haste, spellcasting disabled
11. Gates in this Nabassu on Point. It will vanish after 2 turns.
12. Creature target is affected by Hold Creature for 70s. Nothing happens if the desired spell used a Point target.
13. The Lightning Bolt spell is cast at the target. Nothing happens if the target was the caster -- see the Bugs section for an exception.
14. Target suffers from 100% spellcasting failure and -4 penalty to THAC0 for 1 turn. Innate abilities can still be used.
15. Target suffers from 100% spellcasting failure and -4 penalty to THAC0 for 1 turn. Innate abilities can still be used.
16. 80% of gold on the target is destroyed

So, about 16 negative (and some of these are debatable) effects out of 100 or so.  Of them, I'd suggest that they mostly cause increased chaos, but may be able to played around.  Only the Gold and the ones that affect the caster are potential reloads.  So mostly it's just going to be a bit more random.  I'd want to check the impact of the change at a range of levels, since at lower levels you are going to have less ability to mitigate unplanned happenings, whereas some of these are going to be less of an issue at higher levels.

[temnix]

I see that the chance to cast a spell successfully is quite low on a surge. The idea has to be culled.