So I tried Sigma DP1 Merrill...it could use some changes

My friend told me he bought a "worst but really good" camera from ebay for 300$ used. It turns out it was one of the Sigma DP Merrill cameras with shorter lenses. We shot it during the lunch hours and was both pleasantly surprised and disappointed by it.

Everyone's raging about the image quality and it is good...in good light. Once we got the raws out and opened it up in Sigma software, it looked amazing. The contrast in edges are amazing and even when magnified because there is no bayer noise blurring the lines. I liked the colors and I must say one of the nicest APS-C image qualities.

However, everything else are less than pleasant. Writes are slow, so if you are a pixel peeper, it won't do you any good. This coupled with no image stabilization, usable ISO of 100(I would keep the ISO constant at 100), and resulting long exposure times makes it very difficult to use it handheld. Battery lasts for less than 100 exposures, but it just means you have to carry couple more batteries with you, not the biggest issue. Autofocus is terrible, and as an owner of A7R I was surprised to find a camera that actually had worse AF. Slow, unreliable, and unusable at low light.

So... after only 2 days of use(probably 7 hours total) I came up with a list that would make this camera more or less more usable and more importantly for Sigma, more desirable.

1. Good old fashioned rangefinders. AF is bad, SD write time is slow, and lens is fixed. This is a perfect match for a good old  fashioned rangefinder with split-image focusing screen. It will make manual focusing this camera much faster and usable, and will be better than the low resolution screen. Also, it enforces the mindset of older film cameras with no pixel peeping(unless you took one of those film magnifier thingies with you), no autofocus, and taking time composing your shot because you are not going to get that many.
2. Image stabilization. Sigma makes OS lenses, they clearly know how to do it. It shouldn't be too difficult to couple this camera with one of the OS lenses. Yes, you only have low usable ISO, so what? With a decent image stabilization(least 3 stops), 2.8f or wider aperture, and 100ISO, you can take photos in most light. This is not a sport shooter, poor AF, fixed non-zoom lens, and slow performance makes that impossible. But it will make a pretty good street camera/ travel camera.
3. In-built flash. This camera doesn't have the best sync speed, but with that kind of ISO Performance, I wouldn't mind a mediocre-general grade built in flash. A TTL would be bonus.
4. (optional) Double battery slot? Plus extra added weight will help better stabilize the camera. 

I don't think any of the changes mentioned above are impossible to implement and are necessary changes for this camera to perform as a handheld camera. At the moment, it's something of a large/medium format camera with even worse ISO and speed.

I mean with image quality like that and good usable manual focusing system + long exposure times, it would be a wonderful street camera.