What's your goal?

Is it to entertain? Most of the gear reviews I read through magazine subscriptions, web posts, and online rags are mostly a form of diversion. If it is, then yeah, mixing with unrealistic complementary gear is fine, and many would argue more interesting.

Is it to provide a benchmark for potential purchasing decisions? In that case I think there's far more value in the review to sticking with gear in a somewhat reasonable range price-wise, because it bears a better resemeblance to how users will actually use the equipment.

That said, I have found weak correlation (but still positive) between price and performance of gear so that range might necessarily need to be large anyway.

Hey, if you never compared a $300 piece to a $3000 piece, or a $5000 model to a $50,000 model, we'd never learn where the great-value products are!

Would it just not be possible to do both, include the super expensive piece, and a more homogenous unit? It seems to me getting the more expensive unit is usually the hardest part.