Obviously more troops equals faster progression and more loot to use or sell which impacts the economy. However I would suggest checking the test forum and posts by BB_Alex and possibly the answers to Xenos or in general to other people on the same subject. In short they do not want people to rush the content or get levels too fast.
Also I don't think you can really compare regular adventures to elite adventures as there is a significant gap between the loot and gained xp.