THe ongoing debate, one skill tree sorc

[whyBish]

First I make it a rule to have a minimum of 1 skill point in ALL SKILLS just in case it does come in handy. It makes the bonuses that give you Points to All skill levels or all of certain types of skills a little more valuable.

This can be useful in the case of certain skills, but is most definately not a rule that can be generalised for all classes, and especially not the sorc.
The paladin will have some benefit of 1 point in all skills since many are one point wonders (e.g. vigor, cleansing, meditation, salvation etc.)

However the sorceress only has a few one point wonders (a cold armor, ES, TK, Teleport), and all the rest of her skills are just different methods of dealing damage (apart from warmth, which is not really a one point skill IMO)

If you scatter your points over 20 different damage dealing skills that
a ) cannot be used simultaneously
b ) are not synergies of each other
c ) (to a lesser extent) aren't of a different damage type to your 'main' skill

Then you are spending 20 skill points in things that wont help ever.

Much the same reason why barbs don't usually have one point in each different mastery (cant use them simultaneously so at least 4 are wasted points in the long run), zons don't usually have one point in all skills (especially since the bow and spear tabs can't be used simultaneously).

Necros can afford to have one point in many (though not neccessarily all) skills. Curse tree for instance are all one point wonders, skels golems and revives and an offensive skill (spear etc.) can be used simultaneously and even the different golems have situational uses (and synergies with each other

As to the specific case of sorcs in the original question. I would say that more than one tree depends on your playing situation. Are you single player or multi, HC or SC, usually play in parties with a group of people, or solo or pubbies?

If you have a common group (eg. the Amazon Basin (plug plug)) you can afford to stay with one tree so that you will be more effective against those monsters that are immune to your damage.

If you are solo then you either will need one of the following three approaches as far as I can see:
1) Stay one tree and don't attack things that are immune to you (Very hard in hell but can be done)
2) Stay one tree and get a merc with a different damage type to you (E.G. meteor sorc with an a2 or a5 merc). This is a reasonable option for those that don't mind occasionally taking the time and have the ability and or gear to keep their merc alive. Can be a lot slower going in hell though
3) Go multiple trees so that you have a couple of options. In regard to sorcs, if you are two trees I would go with a main skill in lightning or fire, and have a cold one as a secondary (or vice versa) since the resistance cutting ability of cold mastery is quite handy, and you can get a useful FO or such with 20 in FO and a few points in CM if you can't afford more due to your investment in your main skill.

Hope that helps