Yes, leading is an issue, but as long as you promptly and properly clean it after shooting you should be just fine.

Compared to sabots out of a rifled barrel, rifled "Foster" slugs out of a rifled barrel aren't as accurate, but they should be accurate enough. Only a trip to the range will tell you for certain. Oh, and I've noticed it seems to kick a bit more with a Foster slug in a rifled barrel than a sabot, but neither one even approaches my turkey loads.

Have to say, $1/shot sure beats $5/shot, and adds up quick.