I can only speak from my experience as a complete beginner:
I bought my foil a few months ago... I doubted between the F-one IC6 and the North speedster... the carbon they suggested was too expensive (moses onda + board was 1000€ more expensive)
The seller told me not to take the speedster, because I would outgrow this foil too fast... he said it was boring and slow... be this must be seen from the sellers perspective, he foils for several years on carbon racing machines...
If you are used to drive a ferrari, porsche or whatever and after that you drive a skoda... yes you will be disapointed...
But when you come form a normal kiteboard, even the speedster is fast... I think that a lot of experienced foilers forgot how hard it is to learn...
On my first session I fought for 2 hours with my IC6 (normal mast), I could hardly kite for 50m on it, even not getting on the foil... after that I tried the speedster and that was a piece of cake (short 60 cm mast for the first session)... is stepped on it and went foiling , I gybed (not flying) en foiled switch on my first foil trial ever...
After 1 session on the short mast my brother went to the standard 90 cm mast and he felt no difference between both in difficulty.
Because of a construction error on the rail my TS51 was exchanged by a TS51V2: there is a track system instead of the power box and they moved it A LOT to the back... at least 8 cm... My TS51 with IC6 foil is much more gentle now...
My brother has the speedster with the flexible nose board... I like it a lot, very nice cork pad on the board. De flexible nose seems to absorb the shock when you nose-dive by error... my f-one board TS51 is very stiff and that works fine too...
My brother bought it as a light wind alternative and he is very happy with it... at the moment he is learing the flying gybe. The speedster is not perfect, at higher speeds it makes noice...
I don't think that as a beginner you will feel the difference between Carbon or injected plastic... with a lot of experience.. yes there will (hopefully) be more differences than the price tag and the weight
...
Carbon is much more fragile, and as a beginner your foil will take some beating... I learned in onshore wind with waves (I don't recommend it) and was very happy that I did not have a carbon wing...
On my last session some good foilers went 20 km upwind to another spot and came back... there was a lot of chop and some swell, difficult conditions... when they came back downwind the winner was... the north speedster... he was just laughing at the others on their carbon racing machines... I don't know how this could happen... and the winner was not the most experienced or best foiler...
just my experience...
Nayy