I don't know how balanced the Pro900s will be, as they're known to be a bit bass-heavy. For more neutral you could look into the Brainwavz HM5 or Shure SRH940.
For your uses it sounds like closed might work better. I don't know about the 780s, but the M50s work quite nicely for rock, and a lot of other stuff, too.
Try the Creative Aurvana Lives, or the Koss DJ100.
I think for information on flagship-level cans you're better off asking in the Summit-Fi forum, as few people here will have heard both, or even any of them.
First of all, what does "1000+e" mean? Is it USD, or some foreign currency? Also, you're really considering 2 polar opposites, between a single sub-$200 pair and a flagship-level setup. At the end of the day, it's really up to you how much you're willing to spend to make your music sound good. How much does music matter to you? At the end of the day, it's really up to you. The M50s are nice though, if you can get them for a good price.
That's incredible broad, but see if you can find the M50s for that price, or maybe SRH840s, that could work. A bit cheaper you get the Koss DJ100, CAL!, HFI580, etc.
The 840 cables are detatchable, so if you could find a shorter replacement that could work. For portable, check out the CAL and HFI580/780.
For the DAC/amp combo, check out the Fiio E10. The E9 will also work as a standalone amp for desktop usage.
Are you locked into those 2? I would recommend you spend some time browsing around on ljokerl's 214-IEM review thread, which will give you a ton of other choices, and will give you a much more comprehensive analysis than I ever could in 1 post. you can find it here:
http://www.head-fi.org/t/478568/multi-iem-review-214-iems-compared-jvc-ha-fxt90-and-ha-fx500-added-1-8-12
Those two are radically different headphones. For one thing, one is closed and one is open, which makes a big difference depending on your usage environments. They'll also probably need an amp to drive properly, so factor that into the cost. Since the 900s are closed and a bit bass-heavy, they'll give you significantly more bass, if that's what you want. Maybe look into a price point midway where you won't need an amp.
also check out the AKG K81s, or if you want a lot of bass the XB500s.
I don't think the PX100s will be an upgrade at all from the SR80s, unless you didn't like the Grado sound sig. For more bass, maybe try a closed pair (which the PX100s are not). They are very portable though, if that's a priority.
Check out the M50s, SRH840s, HFI780s, Phiaton MS400s, M80s, HD25s, etc, as well
this thread. The last 3 on the list also look pretty good IMO.
Look into some of the cheaper brainwavz or MEElectronic IEM models. The monoprice might work too, though they look odd, and the build is not the best.
Definitely add the M50s and SRH840s to your list, and maybe the HFI780s (No remotes, though). The AIAIAIs aren't known to be the best headphones for the price, but are nice portables and have good bass. Also, you don't want open headphones if you'll be using them in any kind of noisy or on-the-go situation, because they leak a lot of sound in and out. For 3-button remotes, try the V-moda M80s.
I don't think the open cans you listed will do that well without an amp, and won't suffice if you plan to wear your headphones portably. The closed headphones seem to fit you more.
Again, Summit-Fi might be a better place to be asking these questions, though if someone here can help you, that's great too.
RSA, iBasso, Step2Dance, FIIO... I will see.