Metagame shift?

So I've noticed a pretty big shift in the metagame of 40K recently; namely, the switch to fully mechanized armies with lots and lots of melta weapons. This definitely means that the Imperial Guard have skyrocketed to the top tier, but it also means that the humble Tau are now back in the ring.

With S10 Railguns everywhere and S8 Fusion Blasters that are also melta lying around everywhere, the Tau suddenly find themselves close to something of a competitive army once again due to the prevalence of armor. Don't get me wrong, they still have their problems, but in the hands of a skilled player, Tau can win. They could before, but even more so now.

I've been building up both my Guard and Tau force ever so slowly; I've decided to go ahead and "finish" my Tau; but I've also discovered that you'll never truly finish any of your armies, so let's just say my income that is dedicated to the hobby is currently dedicated to expanding the Tau :-p

I'm sure I'll get back to Guard eventually, and especially if I ever do a tournament. I like Tau, and I do think they're close to competitive again, but a good mechvet IG list will always bring the pain, and in more ways than the Tau can cope with effectively.

As for my specific plans for expansion; another XV8 and XV88 are called for, certainly, and perhaps another Piranha or two.

The Guard list is significantly larger; Leman Russes, lots more Guardsmen, Valkyries, Devil Dogs/Hellhounds...

When will the madness end?