I'm not quite sure if this is right place to put this, so if it isn't, I do apologise. However, in the process of designing some lists recently, a thought struck me.
I usually run 1,500 points of Eldar, and recently entered a 1,000 point tournament. At first, my plan of list building merely involved taking my 1,500 points and getting rid of 500 points. Several hours of number crunching, hair extracting and general fustration later, I wrote this off as a pointless exercise. It was only then I realised that going to 1,000 from 1,500 (and vice versa) requires a totally different mindset to designing and playing a list.
Consider this, in 1,000 points, arguably two of the best competitive lists, Nidzilla and Mech Eldar, are either unviable or greatly weakened. Nids don't get Elite Carnifexes at 1k, and Mech Eldar simply don't have the points to spam Falcons. That's the metagame shifted hugely already.
So if these lists are nerfed at 1k, what lists gain? In the process of creating my Eldar list, the one comment I always heard was, "You'll struggle against hordes". Indeed, hordes at 1k have the points to both field lots of bodies, and create relatively balanced lists as well. I could saw Horde Orks especially dominating 1k, with Gaunt Horde Tyranids (maybe dropping a Tyrant for Tyranids Warriors + Broodlord) coming in close behind. Every problem you have at 1.5k with simply not being able to put everything down is multiplied. I could also see shooty horde Guard excelling in such a environment, maybe towing along a Russ or two as well. Maybe you can argue that 1k simply shifts away from dominant lists into other dominant lists, and there is merit to that. But the dominant lists in 1k would be due to sheer numbers, insteads of any inherent weirdness an individual army possesses. Thus, more variety would be possible.
Also, in 1,000, creating a "balanced" lists is bloody hard, if not nigh on impossible. Again, you simply don't have the points to both shoot and assault in equal measure. Attempting to do so will results in both been done poorly, usually with fatal consequences. Consequently, I believe in 1k armies play more to their "natural" strengths. For example: Tau will shoot almost exclusively (well, then again, Tau usually shoot exclusively at ALL points levels.

) and Tyranids will hurl gribblies into combat with gay abandon. Of course, you will have some counter-assault or shooty units, but any more than 1 that deviates from the main approach is asking for trouble.
Luck also plays a more important role in 1k. In 1.5k, the loss/underperformance of a single unit due to bad dice rolls can be bad, but not debilitating. In 1k, such misfortune can be fatal. You may only have 2-3 Lascannons to go round, for example. The aspect of luck is probably the biggest turn off to playing smaller games. People don't want a dice roll to decide the game, relying instead on skill. But, at the end of the day, Warhammer IS a largely luck-based game, and often, some of the most exciting games come down to single dice rolls.
Lastly, in 1k, some utterly obscene lists can potentially be made. I'm sure everyone remembers the Avatar + 3 Wraithlords in 500 points list in 3rd edition, that many considered a crime against humanity.
OTT armies in 1k are even harder to deal with than
OTT armies in 1.5k. Therefore, in 1k, an even stronger "contract" between two players to tailor their army lists for an enjoyable, yet competitive game, exists. This, in turn, leads to a friendlier, hard but fair game.
So, in conclusion, now I think about it. 1k games can be more varied, more "natural" (in terms of army styles), more exciting and more friendly than 1.5k games. Also, they're over more quickly, and cheaper on the wallet. As a student, this is obviously important to me, since I have enough demands on my time and (limited) finances.
Apologies if this comes out as a wall of text, or sounds a bit preachy. What I'm looking for really is people's views on different points values, 1k, 1.5k, 1.85k, 2k, whatever. What are the benefits and drawbacks of playing at that level, and what armies benefit/suffer in that environment. This isn't supposed to be a "what is your favourite level" discussion, although, obviously, people will have their favourites. The point is to discover if you're greatly missing out on the variety and fun of Warhammer
40k by restricting yourself to one points level exclusively.
Anyway, I shall now get off my soapbox. If you read all that, thank you, and feel free to add your views.