I just restrung a commerical mando yesterday with Aquila Nylgut mandolin strings. You have to search them out a bit, and they are $8/set but they sound really great - way less harsh than metal strings but still very loud and clear.
Being nylon, they take several days if not weeks to fully settle in. We had them on a uke in the house, and were really pleased how they sounded compared to cheaper nylon strings. Much clearer and louder.
A good altermative to consider if you have concerns about neck seating under the stress of 8 strings of metal.
So far I only put on a single set of 4, not paired courses.