It's not like there needs to be any competition between schemes, but I do wish some regular league people would play intermediate more. Here's my two cents (and my only intention would be to get people more interested in inter):
As someone who's played both elite and intermediate for years, I think the skill cap for intermediate is noticeably higher. I believe the reason for this is largely due to the huge variety of situations you come across in inter, as lacoste mentioned, which come into play due to random placement, the extra worm count, the ability to rope knock, and the addition of jetpack, low gravity, and select worm. With so many worms in play, kill-spotting becomes something of an art, and it becomes crucial to use all of your opponent's turn time as well as some of your own to determine an optimal kill. Moreover, the number of kills is only half of the equation in executing an ideal turn, since you have to determine the most efficient use of your utilities.
And conservation of utilities in elite is really only a microcosm of conservation in inter. In elite you generally just have to consider your two ropes and SS, and it's fairly easy to determine how many of those utilities you need to hold onto in order to win or potentially win, and considering you'll usually need at least one such utility for SD, there aren't many combinations of rope / SS usage open to you (not that it isn't hard to determine when to use those one or two utilities). In inter, conservation of utilities also becomes a major skill, requiring you to continually attempt to make your opponent waste resources / avoid worm combinations that sap you of your own resources.
Probably due to the sheer number of combinations of jetpacks / ropes / worm selects you can have, there are many opportunities for efficient and inefficient uses of utilities within a single game; it becomes necessary to consistently make wise decisions in resource allocation. There's also quite a bit of fun in the heuristics of utility conservation, based on their own previous game experiences people develop wildly different styles, and there are simply too many options to ever say for certain whether a certain rope usage was ideal; just rarely any situations where you're clearly forced to use any given utility.
Worm selects constitute another big skill that you don't deal with in elite, and they take a lot of time to learn. It's certainly another heuristic factor that takes hundreds of games to get a handle on, simply because you can only see certain aspects of what will happen more than a few turns ahead, yet you need to prepare for the worst case scenarios and use select worm to find efficient worm orders for the next several turns accordingly, hopefully staying one step ahead of those scenarios. You'll constantly find yourself having to plan important aspects of the next two, three, and often more turns since you have some freedom in worm order, while in elite you will often be bogged down in BnG, or in situations where the same few worms will be forced to perform roughly the same actions each turn and there's no need or desire for any particularly creative planning.
Aside from big skills, intermediate tends to have way more opportunities to test your knowledge of the game and practice little skills, e.g. rope knocking in general, hitting 2 worms with one bow, knowing mine / bat distances, mine drops, grenade / HHG drops, cow skills, knowing when SD will come, knowing when a worm will slide forward or bounce back from the ground or ceiling, etc. And while elite does require 'motor skills' like BnG and SSing, inter requires pretty brutal precision with most all weapons, in both LG and non-LG modes.
In short, I find intermediate to be more strategic and complex, mainly because it requires several large skill sets that are not so prominent in elite. Though this has little to do with one scheme being better than the other, since fun is a big factor. I've just been having more fun with inter because it always seems I can get better, and there are always interesting situations that require creative thinking. I disagree with ropa and dark though, intermediate has progressed a lot in the past 4+ years almost entirely outside any regular leagues, and there are quite a few specialists, so this 'gap' isn't going to close much more than it already has.