I teach exclusively piano, so I haven't checked other instruments. But in piano exercises, there are no ties, in any level, in any rhythm. This would be IMMENSELY valuable. I would say essential. I swear by SRF, but I do think any sight reading system that wants to be taken seriously shouldn't exclude this basic rhythm that is unavoidable in real music. I'm puzzled because I searched the forums for this feature request... and apparently no one has ever mentioned it before?