well i wouldn’t recommend the ns7 unless hes going the turntablist route, in which case i would recommend 2 technics 1210’s traktor scratch pro or serato and the rane ttm57.
If he is just going to be playing at home and not to many house parties the 4d/2000’s is superb but very bulky and probably abit of overkill + your going to have to map it to traktor or download one ,i suppose but you would probably want to change it to suit your requirements , im not to sure about the db4 yet havn’t read much on it
Imo i would go with 2 cdj 2000’s, Djm 2000/800 or a xone 92 (not to sure about the db4 yet), Kontrol x1, traktor scratch pro, hdj 2000’s and some krk rokits or vxt’s thats really professional and you’ll probobly never have to upgrade it also leaves options if you want to add ableton into your setup or maschine or something along those lines. This setup is reasonable portable within a flight case, but at club gigs your only going to have to bring along your sound card, labtop and kontrol x1 or 2
I wouldnt say 4 2000’s as it takes alot of skill to use 4 decks efficiently and well you’ll probobly find you wont use more than 3 and thats only in some cases, I might use 3 once every couple of nights if i want to quickly put a song in and then mix it out just to tease for example, It certainly doesn’t warrant buying another cdj.
Especially if your using a software like traktor you’re going to have 4 decks internally that you can control via controllers for samples etc, traktor will be coming out with an update soon so that traktor pro/scratch encompasses the sampling feature
I guess it all comes down to the type of djing (turntablist, timecode, midi controllers) and were he wants to dj. if you’ve got any more questions dont hesitate to send me a message i’de be happy to answer, im sorry this is probably abit hard to read its probably quite disjointed as im writing an english essay while writing this thread, A million things be going through ma brainz!
Some things to have a look at:
http://www.youtube.com/user/ellaskins - youtube channel obv
he’s has lots of great tutorials for beginner dj’s and helped me when i got started
http://www.traktorbible.com/en/traktorbible.aspx - this is a great book and i’ve been meaning to get someone in the us to pick one up for me.
http://www.skratchworx.com/newspage.php4 - has some great reviews and articles
and of course the djtt home page and ean’s youtube channel, those are just some off the top of my head hope this helps!