Mick, HIE was substantially easier to shoot than most of the near-IR films now on the market. It had sensitivity quite a bit further out into the IR and so haze is therefore much less of a problem. Also, if you look at the curves for films like Rollei IR , superpan, etc. their sensitivities drop off steeply right across the range where you want to filter them to get optimal Wood effect. The results are therefore much less predictable.