I guess it all depends on whether you are going to the concert to take pictures or listen to music and watch the show... ??
I would not recommend that you potentially spoil the experience of watching the show and listening to the music by trying to "smuggle" in a bunch of gear that might risk you either - not getting in - forcibly ejected - getting your gear pawed by some goon - possibly prosecuted....
Bands these days - big acts like U2 - don't take kindly to psuedo-professional photographers trying to "steal" their image - their image is their livelihood and stealing shots during a concert is akin to you stealing someone's images of their website... Sure it's possible - but that doesn't make it right...
Sorry if this all sounds a little righteous to you but you should decide if you are a concert goer or someone who is looking to impress their friends by showing off your stealthy pictures of U2 - then again perhaps I'm just being a Devil's Advocate
Frankly, I suggest you leave the gear at home and go and enjoy the concert - after all that is all you are paying for when you buy the ticket...
I just don't get the whole "I am traveling 1,000s of kms to see one of my all time favorite bands but I'm willing to risk my enjoyment ( and maybe that of your friends or family that are attending with you ) because I want to take a few shots with my pro gear in the dark".... ????????
If the pictures are worth the potential risk to you then buy or borrow yourself a decent smaller P&S digital that has a 1000 x zoom and snap a few shots with it.....
This isn't like being challenged by a security guard on a public street for taking a few shots of a building he works in - when you enter the concert with restricted ( and purposely hidden ) photo equipment you have already broken the rules - taking shots is strike two - - resist a bit when you ARE confronted and you'll get what you got coming.. Then you'll have a REAL story to tell us when the smoke blows over...
When I am driving I tend to miss a lot of the scenery so I am always envious of my passengers - - When I work an event as a Professional I also tend to not absorb much of the experience of the music or performance either...
If I had to shoot while concealing my camera and always be on the lookout for security or whether the guy standing next to you gets pissedoff and turns you in - I don't think that would be fun AT ALL...
Good luck in whatever you decide to do...
Cheers...