This idea has been kicked around in pieces before, though I think this particular combination may be unique.
Mount a Roton blade system on top of the shroud of a standard launch vehicle. Power it up before launch such that it is supplying perhaps 20% of the total thrust at sea level. At the 10/1 Isp gain early on, this would be a serious enhancement to the vehicle performance.
If there is a launch vehicle problem, the payload and shroud are detached to be accelerated out of harms way by the already thrusting Roton unit using it as an LES system.
The Isp gain will fade as it climbs out until in vacuum the tip rockets are at perhaps Isp 300 which is less performance than the main propulsion system. When the shroud is ready for detachment, it is separated from the launch vehicle and pulled away by the Roton unit.
The Roton unit is used to control the shroud reentry and to guide it to a recovery vessel where it auto rotates to a landing.