Played a few days of MP now after beating the game.
I have played a lot of both sides now. And I can say being the invader/Julianna is generally more challenging than defending as Colt. Colt simply has more advantages to his side. Biggest of which is because Colt has 3 lives! But man is it satisfying when you still kill him 3 times in a row!
You get points towards lvl up even from 1 kill. So a full clear is not necessary to keep advancing. But still, the full clear is what we strive for.
If you have patience and don't try to play it as somekind of 1v1 deathmatch game Julianna can be devastating. The amateur move is to try to camp the radio antenna. But the disadvantage to this is MOST Coles expect this. And basically you are going to be a pretty unfair 1v1 in a zone Cole probably knows pretty well.
The technique that works best for me is to ambush from creative places he is not expecting. Either in route to the antenna. Or en route to the Visionary target.
The first kill is usually no problem if you get the jump on him. Its kills 2 and 3 that will be the challenge. And generally it is better to relocate immediately after each kill. Trying to face him head on in the location you just killed him is usually not going to go your way. Because he has a full health bar and knows your location now. Julianna's biggest advantage is suprise. Because this is not Dark Souls. Fights in this game are over in seconds once the gun fight starts.
I generally run into 2 kinds of Cole players. The very stealthy type and the very agressive kitted out for pvp type. And the agressive Cole is usually the more successful one on average. Simply because like I said, they have 3 lives. And they know you don't. And generally thier gear and loadout will be better. Because it is very easy to aquire good trinkets and weapons for Cole via the story mode. While Julianna only earns an handfull of random weapons and trinkets each hard earned level up.
Some interesting things many inexperienced players don't seem to know: Sound does not carry very far at all in multiplayer. It is a MUCH shorter range than you would expect. Cole could be in a full on gun fight at a range somewhere relatively near that you think you should hear and you will hear nothing. Real world physics do not apply here.
So forget about waiting for foot step sounds. Even if he is at full sprint you will NOT hear him until he is VERY close. Like a few meters away.
But the funny thing a lot of players who try to play a stealth Cole don't know is how LOUD Shift is. When you play PvE in the story mode NPCs dont hear Shift. Many Coles have a false sense of security because of this. But the Julianna player hears Shift or any any power usage VERY well.
Its like ringing a dinner bell. 90% of the that is how I know a Cole is around because I hear him Shift.
Anyway, killing Cole 3 times is a real challenge for Julianna. It requires a lot of patience, or the Cole player has to be a complete noob. I go in playing as Cole intentionally for PvP now. And if the Julianna is very good, maybe they will kill me once maybe twice if they get lucky. But three times is very unusual. I would have to fuck up pretty badly. A knowledgeable Cole has an overwhelming advantage.