Lightweight Shoes for Marathon?

The start line for the VLM (my first marathon) is looming ever nearer and I know I need to be training in the shoes I want to run in as of... well... now.

Me: I am short, of average build and overpronate, with wide (D-width), flat-as-a-pancake feet. I've been training for 1.5 years to transition to fore/mid-foot striking, which I now maintain well, except after my calves and achilles sieze up, in which case the heels involuntarily come back to play!

• I love the lightweight responsiveness of the Womens Lunaracer+ 2 BUT they are too narrow in the box for me. I ran a half-mara in these and they killed (but darn, they are fast!! Despite the pain, I still opt to run my long distances in these over my other shoes). 
• I love the fit of my New Balance 768s (the only brand that offer size 4-D, and thus the only shoe ever to not give me any blisters, ever!) BUT they're so clunky and heavy, I feel really slow in them.
• I love the Newton Lady Isaac S because they make me feel light and bouncy BUT I'm unsure of running 26.2 miles in them, plus they blister my instep. I currently use these for training runs around 4-ish miles. I've been tempted by the Distance Us, but am guessing the fit will be similar...

I've also tried Asics 2140 and Saucony Pro-Grids but those are total no-go's; I get blisters within 2 miles and they are too painful to stand beyond 20 mins of running.

So ideally I need something as lightweight as the Lunaracers, but with the width options of NBs. Does any shoe like this exist?? Can anyone please advise, before it's too late?

qiping, I'm afraid your image doesn't display! Please could you repost?

 Thanks Al, I'll look into the Brooks for sure, seems like a reasonable price point.

Quick update, I popped into Sweatshop for some advice. It sadly looks like NB don't do any lightweight shoes in a ladies D-width at all! (why don't they think that wide-footed runners want a nice speedy racing shoe??)

They first recommended the Nike LunarElites or LunarGlides... the Glides slipped off my heel quite a bit when I took them on their treadmill though, and I'm not sure the Elites are wide enough for me either. 

But they also pulled out a new one for me - the K-Swiss Blade Light Run. First impressions were that these were pretty roomy and very light, though I've since been on the net and found that another similar option, the "Kwicky" Blade Light Run (Googling comparisons between the two are quite tough when they have virtually the same name!). Has anyone had any experience with either of the two?

Dancing in spikes, not exactly there... more like all along the instep of where my arch ought to be. It's where I get blisters in every shoe that isn't a D-width, it would seem so far.

 I do switch up my shoes a whole lot though, mostly to ensure that my forefoot running stays in place regardless of the shoes I use.  The past week, I've run in the Lady Isaacs (3 miles), the Nike Lunarracers (15 miles, plus a speedwork session) and the 768 (short slow jog). 

Speaking of Newtons, though, I'm actually thinking of joining the Newton Ambassador Program just because it'd be a great way to try the Distancia U shoes, too... if I like 'em, I can get another pair for £100 off; if I don't get on with them, I can return them within 30 days. Sounds like a win-win.

Otherwise,  I've been researching and I've seen some suggestions that the Brooks ST5 might be too geared to heel-striking... that Green Silence might be better? The Kwicky Blade Light apparently lends itself to forefoot running too, with a foamy sole at the forefoot that hardens with speedwork. I tried this shoe and the Blade Light Run... I could feel the medial post in the Kwicky, but not in the Blade Lights, and wasn't sure if that would equal "yay, support for long distances!" or "noo, blister time". The Blade Lights are certainly roomier but I worry about lack of any support at all.

Yikes, at this rate of over-analysing,  the Marathon will come along and I'll still not have any shoes

I use nike lunar and although its a little more expensive, I got a pair of LG 2 and 3's in Wide size (which you can get on nike ID). I struggled for years being told by running shops to cram myself into size 9 asics and adidas when all I needed was a pair of 8.5 wide lunarglides. Never had a shoe fit so well.

Running snobs will probably slag off nike (which is odd when you think their R+D budget eclipses the rest....and paula radcliffe and mo farah wear nike on the road...and they arent bad runners) but not everyone has the same feet. Once you get something that fits, the brand doesnt matter. I've had less injuries and got more miles out of my lunarglides, not to mention less blisters. 

Im using eclipse 2's for every day training to keep my underpronation in check and bust out the custom wide lunarglides on race day (So I can extend their lifetime since its harder and harder to find brands who do wides)

Fizzipop - I'm running in Newton distances at the moment, and loving them for short distances. I wouldn't use for a marathon though - would use the Gravity/Motion (depending on if you are neutral or stability shoe wearer) instead.

Thanks so much for all the suggestions, everyone! I've ordered the K-Swiss Kwicky Blade Runs, Saucony Kinvaras and Brooks Green Silences to try (I asked about the ST5 but was warned it might not be so suited for me, as a forefoot runner).

 Wayne, I have no qualms about Nike at all... those Lunarracer 2s are still the best shoes I've owned so far, were they not too narrow for my D-width feet! If only I could get those customised, the search would end...

Dancing in Spikes, that's helpful, thanks. I saw the post on Newton's fb wall about there only being a 3oz difference between the Motions and the Distances, so there shouldn't be much in it; I guess I'm just taken to thinking that lighter is better! I'll probably try them both.