It's become clear from the recent
poll that there is not a lot of interest in high-res mode. From the reasons given, it seems that some people simply prefer low-res, whilst others seem unsure of how to best make use of it, or see it as extra work.
The physics reason remains a fairly compelling one to stick with low-res, but even then I'd assert that it doesn't make a massive amount of difference. I have played in hr mode since its 12.8 inception and have never noticed any problems directly relating to pixel precision during gameplay. In particular, the hr sprites were carefully designed to fit their low-res masks - I should know!
Since there have been other high-res lemmings engines (WinLemm, (Super)Lemmini, Mac, PS2), I'd even go so far as to say that low-res doesn't give a visual tactical advantage either, since the ability to judge things just by looking is based on experience rather than explicit visual information, and most players are likely to have encountered at least one of the aforementioned engines (and thus experienced high-res lemmings at some point). By extension, playing in hr mode for any length of time will allow the player the adjust to the new resolution anyway.
All of this being the case, I'd like to put forward the option for creators to
specify a resolution in the level files, meaning that NL will engage high-res whilst playing that level recommend that a particular resolution be used.
If that's not do-able, then how about for packs (this might even be better, since it then wouldn't have to be done for each level individually)?
Designers may spend a lot of time creating high-resolution graphics in order to take advantage of this feature, only to find that
the majority of people are playing it in low-res, and thus missing out on their work. If certain levels
forced hr mode (and then it reverted to player choice afterwards) specified a recommendation chosen by the designer, then
a) designers would know that their work is
being more likely to be viewed and played as intended, and
b) players who normally use low-res mode would be encouraged to appreciate high-res mode occasionally.