Hi,
I've bought a model of Yak-3 of HobbyBoss, and compared it with the Hasegawa.
It is very similar, with the same size and shape, and, eventually, the same defects.
It has three more defects: the fuselage section is more squared (the tup curvature starts 1 mm above the tail surfaces, it should be 1 mm below), a small outlet on the fuselage side is barely visible, the wingroots intakes should have their lip anguled downwards and outwards and thinned, and the canopy sides are very slightly rounded instead of flat. The first two defects can be corrected with less than an hour of file work, the third is scarcely visible and, on my model, I'll use the second canopy included in the Hasegawa kit.
In consideration that the HobbyBoss costs 5.80 euros and the Hasegawa about 20 Euros, I think that it's an acceptable alternative.
Some defects are clearly visible on both models: the exhaust stacks are too close to those of a Me-109 (hard to remedy!), the spinner is too sharp (I'll try to replace it with that of a LaGG-3 of Toko, late version), some panels on the wings should be filled and some parts of the retraction mechanism of the landing gear should be deleted.
Massimo