I have no idea what this has to do with the new Mars lander, but it sounds like a pretty cool concept.
If you can shoot them down intact, you can recover the Elerium-115. It is possible to get a game in which landing sites aren't very available to the player, so it wouldn't be kind to require a large stockpile of Elerium to win the game if there isn't a fallback, failsafe method of obtaining it.
The idea of an Electro Magnetic Pulse (EMP) craft weapon for disabling UFOs is a beautiful one!
However, I think the current combat mechanics, wouldn't work, as damage is applied to the craft, until its forced to crash.
If you shoot down a craft with cannons, it will always remain fully intact as if it had merely landed. This is due to the low amount of damage done per hit. Depending on the amount of excess damage done, the power sources either do not explode, make a standard explosion, or make a large explosion. With enough excess damage, you can destroy the craft. Weapons that hit harder have a high chance to cause excess damage to the ship. For instance, a medium or large scout shot down with stingrays will generally always have a standard explosion from the power source. In the medium scout, this levels the entire inside of the ship and occasionally a couple walls; in the large scout, the central room is blown apart along with most of the inner walls. But a large explosion will tear up the entire inside of a large scout along with some of the outer walls, and will utterly flatten a medium scout, leaving a square of rubble on the ground.
Cannons (10 damage) hit light enough to always knock down a small scout intact (though you get no Elerium). My pulse cannons hit for 20 and my plasma cannons hit for 30, considerably less than the small-scout-blasting stingrays (70). They may pop the power source a lot but should fairly often preserve them. I'll need to test how well this actually works.
I am aware that there may exist a version of X-Com in which the damage of the weapon does not affect the status of the power sources; also, there may be a bug in which if you save the game after crashing the ship and before landing at the site, then re-load before you land, apparently the game does not store the hit information in the crash file and its status will not be connected to how it was shot down. And I haven't actually done much shooting down UFOs yet in Open X-Com. I'll get back to you on how close it is to what I'm used to.
Anyone know how to take a screenshot from within Open X-Com? I have somethings to take pics of, in particular I'd like to show you guys the difference between a small or large explosion in a medium scout.