Just got through my second playthrough, Nightmare difficulty in Deluxe like I said.
First off, actually saying something about the deluxe version specifically (like the thread title says? No way!). For most of the equipment, I thought the cost in scraps and the proficiency requirements were generally too high for what they do. That especially goes for the armor; a lot of them have defense values of 1 and 2 mostly, and many of your party members come equipped with armor that has 2s across the board. High-end armor from the shop has mostly 3s and maybe a 7 on one of the stats, and you start getting comparable equips starting from pretty early in wasteland exploration.
On the other hand, I have to give a special mention to one particular weapon from the scrap shop: The 'Yuza'.
Compared to the Sparrow, it trades 5% accuracy for a whopping 4.5 points of damage per shot on average, and has the same firing rate of 4 shots on Normal fire. Probably the strongest weapon in the game, and well worth the 850 scraps it takes to get it. I saw other weapons with comparable strength to the Sparrow, but by the time I save up enough scraps I'm pretty late in Chapter 5 already. (I didn't do many of the optional wasteland encounters though)
Oh yeah, those 4 starting weapons were pretty decent too. They were pretty strong until you can pull weapons from the barracks, and even after that I used the Psionic Omega and occasionally the Poison Sniper Rifle.
As for the difficulty, I think the jump from Planet Stronghold's Medium to Nightmare was actually smaller than Loren's Normal to Hard. Just now I died to see what game over looks like in this game... >_> It probably helps that it's a simpler game, but also because enemy defense isn't higher than before, so I never got stuck from simply being unable to outrun enemy HP regeneration. That's actually a good move for easier balancing of the game though; I've played commercial RPGs where enemies on the highest difficulty setting have so much defense that all your attacks are doing 1-digit damage, unless you're way ahead of the normal curve on equipment or levels... not much fun if you ask me!
I also tried pulling through without using Shock, which I saw as a broken lategame skill for not giving bosses a chance to move. I was concerned about enemies with powerful special attacks, like the final boss. However, it turned out that there's few enemies that can put a dent in a tank with good armor and Protect, so even if you get lots of status effects piled onto you, you can usually outlast enemy attacks just by defending. (Good thing too, since there's not much you can do about status effects outside of Cure)
Pretty much done with this one now. Judging from the production values and depth of the more recent Loren, I have no doubt that Planet Stronghold 2 will be even better. Looking forward to it!