If you have a good reliable forehand and great court coverage, then your slice backhand would be an asset even though you cannot hit a topspin backhand:
Slice is nice as an approach shot, as a rally change of pace shot, as a drop shot and as a volley shot. The only problem I could see with slice is on a deep ball, and when your opponent is at the net. When pinned deep in the baseline, I would recommend prolong the contact and have more follow=through. And if you cannot pass right away with your slice, use your slice to elicit weaker volley which you can then put away with your forehand.
To sum it up, you can live with slice if you have a good reliable forehand.