the 80mm lens has a larger image circle that you do not utilize. Thus you are using only part of the performance of the lens. This will not be disadvantage for not-so-large prints (usually not a problem together with the already mentioned mag-ratio limitations). On the other hand, the larger image circle may catch more straylight, if your negs are not well masked. Even if you easel is black, straylight usually reduces contrast-transfer of the lens.