I recently started to re play M&M VII, for the first time on dark side(S/D/C/S). My troughs?

1 - Find what you need to do on dark path is much easier

2 - Dark Magic is very powerful. I literally killed an dragon in one round by casting dragon breath and the souldrink spell made some tough fighters like on titan stronghold much easier

3 - The begging is much harden. The quest to get promotion to Wizard was almost impossible thanks to the fact that trapped chests can OHK me, so pick golem parts around the world isn't that easy.

4 - Some enemies like Medusas who was very resistent to dark magic, i found easier to just skip with invisibility or in worst case scenario reanimate some Behemoths to fight then

5 - I wish that i can do a sorcerer only run BUT Robert the Wise will make impossible to progress without a cleric

6 - Quests on Dark Side tends to be much more fun. Also i got an dragon familiar, something that i never had on light side.

7 - I loved the (in) human lich transformation but i wish that i can become an vampire. Taking sun damage and everything. I din't liked that necromancers can use dark magic on VIII but vampires can't, despite not liking much "lich", i loved that this is one of the few games who allow the PC to become a lich.

Here is two screenshots

https://imgur.com/a/Es3YskO

Anyone else did a caster only party and wanna share the experience?

I did a game with 4 sorcerers a while back. The beginning of the game was pretty slow, but once you start leveling dark magic it becomes comically easy. 4 sorcerers is 100% the most OP party that I have ever played with.

You couldn't open with telekinesis?

Sorcerers can't use Master Earth.

Correct. You need the Wizard promotion first. This is a downside of playing without a Thief. Or even a Monk on the Dark Path, who can reach Master Disarm, at least.

It did occur to me later that promoting the Druid would give access to Master Earth, but that still doesn't solve the problem of opening chests that are in corners too tight be out of range of the trap damage.

I've done a run without a Thief or a Dark Path Monk, and traps were no fun. I won't be doing it again. :)

They're indeed annoying. It's gotten to the point where my standard party is (not necessarily in this order) S/C/T/?, with the ? being either K or M or P (I like the paralytic effect of GM Mace) for Light, and another caster for Dark. I find certain skills to be just too useful to dispense with (and I just don't see the point of A or especially R at all).

That sounds about right.

Having used both, Archers are okay; they mix decent melee, good bow, and decent Elemental.
Rangers are good for swinging an Axe and tertiary support for non-L/D magic, and that's about it. Their promotion quests are really easy, but that's about all they truly have going for them.

There are a NPC who can cast GM protection from Magic? If yes, i wold try a S/S/S/S run

There is no NPC that casts Protection From Magic at all. There are some that provide healing (and some also heal status effects at the same time), and some that provide Water Walk, Fly, Town Portal, Bless, and Heroism (separate NPCs, not as an all-in-all), and ones that provide skill bonuses, but none of them provide attack spells or Protection From Magic.

I am not an expert at this game by any means, and did a fun run with no Thief and no Monk, Light path. The Archer was the best at perception, and damage avoidance was good enough to still get most of the chests (if not all...can't remember any I missed but was not a "completist" run--PACS run).

So, go with what is fun to you (whether that is powergamey, trying different classes out, or whatever floats your boat). For me, it was roleplaying for the two non-pure casters (I knew I wanted CS) with 4 different classes and a good balance of skills...and knowing next time I would do dark path, I decided Paladin because thematically he seems more of a "light path" character, and Archer because I remember foundly in my childhood playing MM2 and the archer I had there did great, so since then I have always thought archers were fun to roleplay in CRPGs that had them as an option.

Regarding GM Protection from Magic, I think that is why many people claim CSSS is strongest in MM7.