Glad to help. :)
I purchased DA:O at release, too, and I agree: The DLC was a pain at first (especially so lacking a high-speed Internet connection at home). After some initial frustrations (it was an experiment for me, too), I learned how to perform an easy offline install using backups of the DLC and promo items. Ultimately I was okay with it because it seemed that they were attempting to discourage casual piracy but intentionally leaving a back door for players who want an offline, CD-check only experience. Not ideal, but workable.
I agree about patches and DLC requiring download and install via the game interface being problematic. Your preferences sound similar to mine, but I suppose that's not too much of a surprise given that we're both here on GOG. ;)
As you mentioned, patching NWN2 was a hassle... patches weren't cumulative iirc, just a mess of successive patches in an archive... I also repurchased it here. I've kept a few games on disc that are sentimental to me or collectible or not available on GOG, but I've gone more-or-less all digital now, too. Ironically, Steam's intrusion into the physical market (replacing disc checks with client-based DRM) was a significant factor bringing me here to GOG.
Katsunami: EDIT: Ordered the Ultimate Edition for PC on eBay; it's sealed and brand-new, says the advertisment.
Pity that I never got to finish the game and expansion. I wonder if I can sell this game. I assume the purchaser will need to buy all DLC because that is tied to my Bioware account. At least I can use that account to download the latest version of the Witch Hunt DLC.
There's no need to register the Ultimate Edition to your Bioware account unless you plan to use Bioware Social Network features (and if you do plan to do so, you might not need to register the Ultimate Edition if you already have an account from a previous edition of the game). The DLC are included on the discs. Install from the discs, install the latest DA:O patch, install the patched version of Witch Hunt, install the promo pack, edit addins.xml, done. Complete offline install, no login required to play (and if desired you should be able to sell your copy later without issue). You've purchased the Ultimate Edition and can download the game patch, so you should only need the patched version of Witch Hunt and the promo pack (PM me or take a swim in TPB).
Katsunami: I'm now in the middle of a EasyTuTu BG1 run (just about to trash Tazok), I'm in the middle of an Icewind Dale 1 run (just entering Wyrm's Tooth), and I want to do a BG2 run after I finish BG1. Then I'll start DA:O again. (But I'll install it as it arrives, so you don't have to wait 5 years for my DLC list.) After thinking about it, I actually forgot almost everything; I estimate I was at around 60-70% or so.
Cool. You'll be set to tackle PE after all that. I need to play those again myself. I started a DA:O run earlier this year but paused it after Ostagar close to leaving Lothering (just haven't been gaming much lately).
I've written two short guides for starting fun rogue and control mage builds if you need a boost getting back into DA:O. Nothing fancy, just a progression chart for stats and abilities and some notes. Not even full builds, just rough outlines that leave room for customization while taking some of the worry out of the earlier part of the game. PM if interested, no worries if not.
One last bit: The Ancient Elven Boots were not fixed to appear in the intended container in Lothering in the PC version of the game and are thus not obtainable by normal play. You'll want to grab one of the mod fixes for this issue if you want the boots. See
http://dragonage.wikia.com/wiki/Ancient_Elven_Boots.