Raff's '2 Caprices' Op.111 are virtuosic showpieces designed to display technical prowess. They likely feature rapid passagework, demanding leaps, and bold harmonic shifts characteristic of late Romanticism.
Developing extreme speed and accuracy in both hands, along with the stamina for sustained intensity, is the primary technical hurdle.
2 Caprices (Op.111) is rated Henle level 7 of 9 — late advanced repertoire, roughly ABRSM grade 8 and above. In the RCM system it corresponds to about level 9.
You should be comfortable at Henle level 7 — meaning you can already play level 6–7 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of 2 Caprices (Op.111) lasts about 8 minutes.
2 Caprices (Op.111) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.