[Klaus]

Yes, probably in X-mount (I'm doing so many tests in E-mount ...)

[Rover]

I guess the old days when you would test the same (third-party) lens models in up to 3 (I thought even 4, but apparently I was wring...) different mounts are gone now. Ditto testing FF lenses on APS-C.

[Klaus]

I think Markus has checked the Z stuff on APS-C.

Generally, the FF borders are an indicator for the APS-C corners.

As far as testing on multiple systems goes - budget constraints ...

[Rover]

I understand. Anything new in the pipeline you would want to unveil?

[Klaus]

Other than the 10-18mm, I'm trying to get my hands on the Tammy 17-50mm.

But I still have to write 3 reviews based on existing lab tests, anyway.

[Rover]

Woohoo, the Tamron 17-50 is exciting. So is the 50-400 - I think if both are ever released in Z-mount, I could just get these and finally leave the Canon gear behind. Would probably be a killer 2-lens solution.

[toni-a]

Woohoo, the Tamron 17-50 is exciting. So is the 50-400 - I think if both are ever released in Z-mount, I could just get these and finally leave the Canon gear behind. Would probably be a killer 2-lens solution.

On paper yes for the first months at least, however superzooms like 50-400 tend to deteriorate rapidly,  with a few exceptions like Canon 28-300.
I know a friend of mine who had Tamron 28-300, he was happy with it the first months then recurrent problems started arising. 
Don't expect a durability and reliability like on Canon 16-35f4, in your shoes I would stick to Canon 16-35f4 rather than going Tamron 17-50

[Klaus]

So far, I haven't tested the 50-400mm because I don't understand its purpose.
* at 50mm, it's too slow to make it useful
* it overlaps with a lot of standard zoom lenses at the wide end - and even with the 17-50mm, you aren't really "required" to fill the gap compared to a conventional 100-xxx.
* 400mm isn't long enough
* it's excessively expensive for what it is. Where I live, both the Tam 150-500mm as well as Sigma 150-600mm Sports are much more affordable. And if I had a choice between 400mm and 500/600mm for less money, I would know what to choose, really. And the Sigma 100-400mm is almost half the price.

The 50-400mm could make more sense in X-mount, maybe. But the value props remain questionable, IMHO.

It doesn't seem to gain lots of traction in terms of sales volume either.

[Rover]

Well take my word for it... I now prefer the 100-400 over the 70-200 (especially on full frame), and coupling it with a wide zoom like the 16-35 I have, or indeed the 17-50, would allow me to lessen the gap which is now quite large (35-100, although switching to DX mode and Large file size allows me to narrow it somewhat without loosing too much resolution) whenever I'm carrying just two lenses.

17-50 and 50-400 would've been a good native solution for me. Inasmuch I've checked on the interwebs, the 50-400 has gained mostly favourable reviews. Of course if I really choose to go full native, I'll have to procure some large aperture options as well because f/4 and f/4.5-6.3 isn't terribly fast by any stretch of the imagination...