I worked on a similar principle. I had the option of giving my 640 XL 3G DS and going for a 950XL. Instead I bought another 640XL 4G DS and gave away the 3G version. Why did I not buy the 950XL?
Firstly, because of the price. I do like the way the 950XL looks though. I find it to be understated and a device that tries to make content standout over the device.
Secondly, after getting onto the Insiders Ring, I downloaded and installed W10M and now have moved to the latest version. I find that the 640XL is like a new device. Granted 1GB RAM, but it sure as hell does not feel like it. And while I am not a great app user, I do have some core apps which I use and I push my device a lot during the day (banking, email, calendar, reddit, telegram, whatsapp, news apps, OneNote, camera etc.). The 640 XL has performed admirably except that I notice that the battery life was a bit better on 8.1.2.
Thirdly, in my assessment, MS is treading water a bit with their WP efforts at this point. Why do I say that?
Firstly, because releasing the 950 and the 950XL with buggy OS was not cool and that too at premium price. Assuming MS is a rational entity (which I believe they are), I think they had no choice but to release these phones now! It felt like the schedule to release was forced onto them.
Secondly, the OS has not been stabilized. This is supposed to happen sometime this month apparently and whatever parts are problematic will be dealt with in Redstone which will be available sometime in the middle of the year.
Thirdly, I am now quite certain that MS will release another set of flagships towards the end of the year and there is a good chance that they may have a Surface branding. Yes, they will be expensive, but MS won't trifle around with the brand by releasing a well designed and well spec'd device with buggy software. And, anyways, by then, the OS, I expect would have stabilized.
And, while it is never a good idea to defer purchases in the tech domain in anticipation of a better device in the future, in this instance, my calculated guess is that instead of spending the kind of the money the 950XL commands at the moment, it is better to settle for a vastly lesser spec'd device but one that is reliable and responds well to W10M as it currently stands.
Thus, my going for the 640XL (and it is a brilliant device, btw!!!).
