I would say not - the LED shining through like that could easily be washed out if the robot was parked under one of the lights providing illumination to the arena. There is no reason not to have the LED mounted to be clearly visible through the armour and all teams manage this without an issue.
Also - there is no way that the LED can be 'brighter' through the armour ! You may perceive a glow around the LED, however that washed-out effect is what will make them stand out less under bright light.
The simple solution to this is to buy an LED that is designed for the job rather than start wondering if the rules flex enough to allow a bodge.
http://uk.rs-online.com/web/p/push-b...tches/6903390/
Connect this up to one of your RX plugs, brilliant bright LED, stainless steel surround, not going to get damaged - job done properly and no need to bodge by trying to shine it through the body of the robot.
Ed