My Initial 500 Point List

So this is the list I put together with the models that I have.

HQ

Archon (60)
- Venom Blade (5)
- Shadow Field (30)
95

Elites

Incubi
5 Incubi (110)
Venom (55)
- Splinter Cannon (10)
175

Troops

Warrior Squad
6 Warriors + Sybarite (73)
- Blaster (15)
88

Warrior Squad
5 Warriors (45)
- Blaster (15)
60

Fast Attack

Hellions
5 Hellions (80)
80

Overall Cost - 498 Points

Any advice for me? I'd like to add some more warriors at 750, and possibly a Talos.

Transports. Walking DE are dead DE, particularly in the squad sizes you are running.

Yeah, I kinda expected that....
Would you recommend Raiders or Venoms though?

Potentially I could drop the Hellions, bump up the first Warrior squad to 9 men, and put them in a Raider with a Flicker Field.

It depends. For raiders you would most likely have larger squads of warriors with a splinter cannon. Leave the warriors outside the raiders in area terrain except when you are moving them. The explosions hurt hard for large squads in raiders.
With venoms I've had success keeping the small squads inside their transport.
Dark eldar have good internal balance so either choice is pretty good.

The most common enemies for me are an Eldar Wraith army, an Imperial Fist Space Marines bunker, and Chaos with Nurgle Terminators. The Venom looks good to me against these guys for essentially ignoring their high toughness advantage.
On the other hand, a Raider gives me a Dark Lance or Disintegrator (although from what I've seen the Lance is the preferable option).

So, at 750 points, does this look any better?

HQ

Archon (60)
- Venom Blade (5)
- Shadow Field (30)
95

Elites

Incubi
5 Incubi (110)
Venom (55)
- Splinter Cannon (10)
175

Troops

Warrior Squad
9 Warriors (81)
- Blaster (15)
Raider (60)
156

Warrior Squad
5 Warriors (45)
- Blaster (15)
Venom (55)
- Splinter Cannon (10)
125

Fast Attack

Hellions
5 Hellions (80)
80

Heavy Support

Ravager (105)
- Night Shields (10)
115

Total Cost - 746 Points