what you have is pretty much fine to start k6, as soon as you have tw. that said, don't expect to top the parse, unless the other players in your group have much worst gear than you. unluckily there are only a few fights where a ranger can shine, and it's mostly where the tanks have switch aggro a lot so all the other dps classes has to be very careful with their dps.
so, just learn the encounters, do your job, and it will be fine.
i guess tiger's gear is a bit squishy for t5/t6, but it's pretty much fine for everything else, especially if you have some survivability accessories (t3 protection neck, ring and cloak, bb ring, jang-shi ring, ardashir neck).
at least in raids you get tokens, and it makes a lot easier to get the last missing pieces, while for some of the khitai gear you just have to rely on luck. for example, the last piece i got of my tiger set was the shoulders, which drops in flame, so in theory it would have been the easiest piece to get...
btw, the only set with a bonus is t6, other than that you don't need a full set, just mix what you get.