I sold my Z4 yesterday and I agree the image looks fantastic.
I was in the same position the last few weeks and not sure at all if there is an improvement worthwhile the investment. Putting aside there is nothing such as an investment in home cinema
i asked around with people I trust and know the difference first hand. The answer has been a solid, yes. The enhanced resolution is one thing but the contrast and blacks will be significantly better. BUT: And here comes the catch. This will only really happen to your satisfaction if you dig deep into your pocket.
I decided to spend almost 4 times of the current price of a Z5 based on the new Mitsubishi HC7000.
My dealer also confirmed it would be a great improvement with a HC6000 (still 3 times a Z5 but coming down rapidly with the new models due this month). If you move to the Z2000, for sure a decent pj, it all depends on your sources and there won't be much improvement. I am a regular and long-term customer, so this is not about making quick money
Head spinning?