I've got a Tyros 3 and the only thing that I don't like is the size. As a pianist at heart I remain very tempted by the T5-76 but that's even bigger and I'd find it difficult to transport.

I have wondered about switching to a PA4-76 as it is only slightly wider than my T3. The biggest impediment is my many years as a Yamaha person and the very significant effort it would take to transfer all my settings, files etc across and (probably more significant) me having to learn a new keytboard OS and layout.

I had a play with a PA4-76 a few months back, sounded fine to me.

As you don't have a huge Yamaha history I'd vote for the Korg if I was in your position and could raise the funds. Nothing wrong with a T4, mind.

I don't usually plug dealers but my local store (Hamilton's, Preston, Lancashire) sometimes has manufacturer refurbished models which may be more affordable although still way more than a T4.