except the tablet isnt really suitable to take outside with you like the vita is.

I guess Nintendo limited the range to avoid problems with lag like the Vita has.  Just a guess.

I have had Wii U and Vita since their respective launch and got PS4 at launch as well... so I tried Vita for Remote Play

It has two ways of connecting. One is via your wireless router (which gives more range than Gamepad) and other is directly to PS4 which has same range as Gamepad. The connect directly has significantly less input lag than the wireless router option.

I was able to play Resogun on Master when connected directly to PS4 which means its pretty damn responsive even if there is some miniscule lag. I couldn't play it on Master when connecting via wireless (dying way too fast). When connected directly, there is probably some miniscule lag, but I couldn't really tell. For me the bigger issue was the controls don't have parity. Needing to touch a zone on the rear-touch for L2/R2 or L3/R3 are the bigger issues than amount of lag.

Does Vita have lag? :O thought it was only a limited framerate at about 30 fps in everygame

On the PS3, it does.  I don't have a PS4, yet.

Got it ;) there's nothing worse then playing with lag... could never play MK9 online because of lag!

Leave me alone in your home with a Wii U and I'll tell you!

I should not be giving an answer to this, but here it goes: it does not, but then you did not have to pay the additional 150 bucks (I myself spent those on games - who woulda thunk it?) for questionable results.

LOL great one!

The Wii U gamepad is great for remote play, even if the range is limited but the Wii U is a console so I'm not surprised.