Are you stuck a few years back? The legend design made the alienware laptops way lighter and thinner than before. While the MSI is indeed lighter and smaller, it's a 15" laptop with dimensions similar to the m15r3, the m17r3 and the aero 17 hdr on the other hand are pretty much identical in dimensions. Both weigh around 2.5kg with similar size. So I really don't know what you're on about. You don't get smaller and lighter gaming laptops at 17" than that unless you want to sacrifice a lot of performance.
Well, I bought the m17r3, just waiting on it to be delivered. Why? Because it's cheaper than pretty much any other laptop with similar specs while having warranty and customer service way superior to most as long as you get the premium alternatives and it's still one of the acknowledged best brands. Of course, if I had a lot more money to spend and didn't care about warranty, I'd probably go with a razer or something instead, but I can't justify the extra price and subpar warranty(at least subpar in my country). It also has 32gb ram which most gaming laptops don't.
Got it with a 12% coupon off and on top to that I managed to get myself a 7% total price refund once it's sent because dell made a site blunder which forced me to re-order my laptop again. Shows they care about their customers. So, close to 20% off a brand new, released-last-month laptop. Also got 15% off on premium plus for 3 years(which is exactly what I needed as I'll sell it after that for 50% of the purchase price to fund a new laptop, can rest assured that it will work until then or they'll fix it for free by sending technicians to my house).
I do agree that the old alienware laptops were very bulky, but so were most laptops. I remember one I bought 6 years ago, quite bulky and was a pain to carry around, but with the slimmed design of this one it won't be a problem even though it's a 17". Also, for the battery issue, it's just a matter of knowing what to do. First of all, turn off that damn crap called tobii eye tracking. It's utter <Mod Edit>. Had it on a m15r2 I tried out last year, ended up completely nuking the drivers until it couldn't even be detected anymore. It slows down the laptop and sends the CPU running all the time so that it never enters an idle state, draining a lot of extra power for nothing. Wish I could order one without it, but at least the problem's solved if you delete all the drivers and uninstalls everything related to it so that it can't auto-install it again. Trust me, it's a power sink. Other than that, the 4k screen is very bright, can easily turn down the brightness a lot. And as with all thin gaming laptops, it's in your best interest to undervolt it for consistent performance and to lower temps along with power consumption. Then you can fiddle with power setting to lower cpu base frequency and also gotta make sure that it uses the CPU GPU when idle so that it doesn't just turn on the gaming GPU randomly when you don't need it. Bet you can raise the battery time to compete with the other laptops then. At the very least 4-6 hours instead of 2-3 hours should be easily doable for normal use. Can't hope for much more when it comes to a laptop specced for performance. Honestly glad if I can at least get 3-4 hours, that's enough, usually never away from outlets for longer than that anyway.