Good video, that.
I read once an article explaining why RR hadn't pursued CF fan blades again (they tried a long time ago, back in the 1970s) until relatively recently. It turns out that with a CF blade you actually need a fair bit of material near the root; not surprising really, it's got to take the entire load on the blade (radial and thrust). That translates into the root actually being quite chunky, which compromises the airflow into the engine core.
Thus RR's position was that whilst CF might be lighter, the core performance is worse. By sticking with hollow Ti blades, RR could make them thin along their entire length, improving core air flow, and gaining performance back that way. Labour costs during manufacture were a secondary issue.
Of course, there's no way of knowing whether the differences add up to a net advantage or not. Both RR and GE's engines are phenomenally good, though on some aircraft (e.g. A380) the RR engine has the weight advantage (can't remember if the GE/PW engine uses CF blades or not).
What is interesting about RR's up-coming Ti-CF fan blades is that now, with different fibres and lay-up techniques, they think that they can make thin blades, all the way to the root. Apparently they've also been concentrating on automated layup. With that being so, RR can now do a light weight blade with good aerodynamics at the root and decent weight savings.
Another aspect common to all CF blades is that it's easy to get any shape blade you like (within reason). If we ignore root area, you can make a blade an ideal aerodynamic shape. With a hollow Ti blade it's phenomenally difficult to shape (RR have become very good at it of course), so there's some compromises to be made between the shape the aerodynamicist wants and the shape the manufacturing guys say they can produce...
It will certainly be interesting to see how RR's blades perform. Thin, any-shape, light-weight fab blades should translate into exceptional fan efficiency.
RR are relatively public about all this, and seemingly have three major technical advances on the way (TiCF fan, GTF, and they're even talking about variable pitch fan blades). Any two of those taken together are really going to advance the state of the art. All three together would be really quite something.
GE are much quieter, but unless they want to be wiped out from the large turbofan engine market they've got to be engaging in a ton of R&D themselves. I'm sure they are.
It's all going to be very interesting to see what emerges from these companies over the coming years.
I've had an opportunity to look at some of the blades RR experimented with back in the 1970s. They were really quite something, considering. Very light. Looking at them it's clear that the lay up techniques employed then were much simpler than GE / RR / everyone else uses today. I've no idea exactly what these ones were, and I'm not even sure that they were usable (look at the resin at the fir tree). These may have been really early prototypes, just to see if they could make something that shape.