I'm just in the process of building this kit; I have the fuselage assembled. Regarding the "humpback", I don't see this in photos of real Yak-1's or in the shape of the Amodel Yak-1, but I suspect this feature is more visible in real aircraft when the canopy is in place - most of the photos I've looked at are of wrecks without canopies or with the canopy pushed open. A worse problem is the cross-section of the real fuselage - it has a very squared shape at the spine; however, this is not difficult to correct to a more rounded shape by sanding.
I agree about the nose shape - the Brengun kit has a curvature of the upper cowling which is very slight and almost continuous from the windscreen to the spinner. Photos of real aircraft and most drawings show the cowling to be relatively flat with only very slight curvature in side view ahead of the windscreen until about 2/3 or 3/4 of the distance to the spinner, at which point the curvature increases slightly but noticeably. Amodel has this shape correctly represented.
A worse problem, though, is that the cowling in plan view appears immediately to be too narrow, especially if you are familiar with the Amodel kit or have spent time looking at Yak-1 drawings. I measured the width at the rear of the exhaust stubs (not including them, of course) from Zbigiew Luranc's Yak-1b drawings - I found that the Brengun cowling is actually about 1mm too narrow at this point, while the Amodel cowling is correct.
While I have not finished building this kit, I would have to say that of the two (Brengun and Amodel), the Amodel Yak-1 is more accurate. On the other hand, the Brengun kit is much more cleanly molded and easier to assemble, especially if you simplify the cockpit assembly as was shown by "Hladik.lada" on Modelforum.cz:
However, I still like the Brengun kit very much in spite of the points noted above, and I will buy more of them.
I think it is almost certain that Brengun will follow up with a kit of the Yak-1b; I hope this kit will show correction of the cowling shape details.
John
