Also, I didn't start this thread because I thought that a cross-over training is not necessary. I think a cross-over is a good idea. The issues are:
- Your prior logged hours don't count after switching from one rebreather to a similar one.
- A prior Normoxic Trimix OC certification doesn't count. I would have to do a complete Normoxic Trimix CCR course. (But only after accumulating 50 hours on the new unit first.)
This is the information I got from Cobalt, who teach TDI and IANTD.
So let's stay on topic please. I don't think anyone doubts that a cross-over course is unreasonable.