Best Light Weight Climbing Jacket

Hello. I am looking for suggestions on a lightweight jacket that I can take rock climbing for long multi pitched and big wall climbing. I currently have the arcteryx atom LT hoodie, but I am a bit worried about the breath ability and durability. Trying to decide if I want to go for something light that can fit on the harness like the Black Diamond Alpine start (I have heard that this jacket isn't that "weatherproof"), or if I should go with a light wind/rain shell that could double as a shell for other activities. Thoughts?

Take a look at the Rab Kinetic or Kinetic Alpine jacket.  They aren’t super light wind shells but are light, fully water proof, stretchy shells.
Dallen 

The Patagonia Houdini cuts the wind like nothing else and weighs in at just 3.6oz. I wore mine in the shower just to see how waterproof it was and only after a while did I get water bleeding through the zipper so I'd call it good for light rain. It has zero insulation and while I'd call it robust for the weight, I would climb up any chimneys with it.

Basically for under $100 you have yourself a windbreaker that sits on the back of your harness that you'll never notice until you need to break it out. OGL gives it their top rating for windbreakers and I can see why.

If its going to rain don't go rock climbing, my pick is the arcteryx squamish as its surprisingly burly and feature heavy for how light and packable it is, also has a really good helmet compatable hood and is significantly more breathable than the houdini. If your prone to really trashing jackets then the alpine start hoody is probably a better option though notably bulkier and heavier.
If you're in the mountains doing more alpine objectives then I would recommend a RAB xenon x as the 2 layers of pertex endurance and 60gsm primaloft gives a ton of protection and insurance for the same as a dedicated waterproof I've used mine in torrential rain and it only leaked on the shoulder seams and the amount of water was pretty negligible as your still warm, all this and still pretty damn small and very light. 

I’ve had/used:

BD alpine start
BD first light
BD dawn patrol
Patagonia Nano air
Patagonia Airshed pullover (a running jacket technically)
Patagonia Houdini 
Arcteryx alpha FL
MH ghost whisperer

That’s about it for the “lightweight” category.

The Patagonia nano air is the most comfortable thing I’ve ever worn, it’s like cozy pajamas comfortable.  But not durable, I wouldn’t wear it while on the rock; and not super weather resistant

The BD first light is less comfy than the nano air; but much more durable and weather resistant.  Also heavier.

I’ve found the BD alpine start to be fairly weather resistant.  I like it, but not if it’s gonna downpour. The Patagonia airshed is even lighter, a little less durable, but crazy breathable and still manages to shed a light rain.  The breathability makes it feel, and actually be less wind resistant.  It’s the least warm of everything listed here.  The Houdini is great but the fabric is a tighter weave than both of these so it’s a bit less breathable, I heat up easily 

The dawn patrol is the heaviest thing listed,  it aside from the Arcteryx hard shell, the most weather resistant.

The MH ghost whisperer is a great insulation piece and is very wind resistant because of the tight weave fabric.  It’s not the most durable though, and will degrade performance in the rain a ton.

The arcteryx, as the only hard shell, is the most weather resistant.  It’s also light and reasonably (for a hard shell) breathable, I have packed it as my only shell before and only slightly regretted it (it was sunny all week, wish I had a wind-only jacket but who would have predicted that?)

If I had to only have one, the BD first light would be it.  

If I had to have an insulation/shell only; id take the alpine start and the nano air.

(Most to least, if worn alone)

Warmth 
Ghost whisperer 
First light
Nano air
Arcteryx
Dawn patrol
Alpine start/Houdini
Air shed

Wind/rain resistance
Arcteryx
Ghost whisperer (once it does wet out it’s bad though)
Dawn patrol
First light
Houdini
Alpine start
Nano air
Air shed

Abrasion resistance
Dawn patrol
Arcteryx
Houdini
First light
Alpine start
Air shed/nano air (same fabric)
Ghost whisperer

Breathability
Air shed
Alpine start
Nano air
Dawn patrol
Houdini
First light
Ghost whisperer
Arcteryx

Thank you for the detailed answer!!

A Houdini is usually all I take for rock multipitch. Cutting the wind goes a loooong way for warmth. Maybe go for the waterproof Alpine Houdini if you foresee yourself getting soaked every now and then?

Another vote for the Houdini. I carry it with me pretty much any time I'm in nature March to November. It's so light/packable I forget it's there until I need it.

I've heard the mountain hardwear kor preshell is pretty nice!