With the Fish On 'French Leaders' you can cast them 'like' a fly line, it is maybe not exactly the same and Ben et al may well cringe (!), but the leader does 'turn over' (with a dry). You can also 'lob' them. These are tapered (knotted) mono leaders. You can see my hero JT demonstrate this on his last River Academy Doov:d.
The disadvantage or flaw in this mono 'technique' as I see it, and as can be seen in the link to the vid I posted on LTH last year on another thread, is that the bottom of the forward loop often touches down well before the end of the leader turns over meaning there is surface tension (drag) on the mono before the fly lands - not a huge problem I guess. Presumably this is all caused by the 'wrong physics' - most of the weight is there in the bottom of the forward loop and the top of the loop does not have enough weight or inertia to adequately overtake (?) the bottom loop. Probably talking pish here...
On suggesting the "Whisper" type lines I acknowledged that, as Marc raised, these would be more prone to surface drag, but also that they would have more weight and inertia to turn over a leader and fly at (resonable) distance, the 'killing zone', whilst still remaining 'stealthy'. It was Jeremy Lucas that pondered whether such lines in the Rio LT Trout range may have a place in LTH type applications. Given that the main advantage of using a mono leader in FN style in UK is apparently to minimize drag, perhaps such Rio lines don't work.......though presumably being thinner and lighter they maybe they would ??
I also agree fully with IA that expansive sections of the Don will be uselss for any of these techniques, especially when the wind blows, fish lying tight in to your bank (all my best fish last season were caught 1-10 feet from bank) etc etc. My river fly lines will never be reduntant unlike JL.
Lindsay (NE Scotland Agent for Ferrets Pheromone)