You never seen it ? I dont need to fly a klingon vessel (i did in OB), to see the extended shield beam and the circle around cloaked vessel hehe....but whatever :-)
Just because you see the effect doesn't mean it actually boosts the shields, once that cloak is engaged shields can't be modified in anyway period, you have to uncloak all the way to begin regenerating shields.
I have to say in higher tiers battle cloak gets less and less useful. Most of the time starting at t4 when someone battle cloaks it usually just means that fed targetting shifts and a buddy of his goes down. Yes there are a few players good with the battle cloak who use it tactically but most just seem to get their friends killed with it. Same with the "run the hell away" manuever usually if you are getting beaten up so badly you have to disengage its going to mean the other side will just rip up someone else on your now down 1 man team.