Is this true?

Well,

Typically the light armour (designed for mages) lets them move faster (staying away from a beating) while casting spells AND gives the best "mage" bonus skills - since thats what the idea of a mage is "in general". So you move faster, cast spells faster and do more damage with spells all together.

Heavy armour, which isnt "designed" for mages in general, gives "fighter" bonuses commonly and reduces movement speed - thus making a person take more of a beating. Heavy armour gives you defense rating - but defense rating is also dependant on strength. So in essence you're strangling a mage by giving him/her gear that doesnt give them "mage" bonuses, reduces their ability to get out of danger quick, and possibly lack the best dmg and levels of spells they can have by spending ability points in "non-typical" areas.

However...there are ppl who make "battle mages," and although they're not "efficient" per-se, they can be somewhat effective, if not fun to play (I had one myself till chunk #2 when mana costs and the changes to a lot of spells and skills made him a lot more difficult to manage while still having fun).

SO...light armour is designed for mages and gives them their bonuses - and would be the logical, efficient and most beneficial armour to use.

(I guess that was the longest yes answer youve gotten in a long while eh?)

Put it this way. Mages with Heavy Armour get owned in PvP.

Heavy armor such as malovent, warmed and cool is still good for lower lvls, where BSoL isnt so tough. This is the all endurance equipment for mages, which if you not carefull will run out of mana very quick. With this gear you are slower then all int gear but still faster then fighters or rangers.