about the skill dlvl:
300 silk converted into skill-edit potions will get you 50x 20% more sp back than the cursed hearts.
It will be quite alot since you are a high level,
but then again, as a euro you can just sit in parties as a cleric and wait for the hearts to drop while you spend your silk on other things.
With the killingspeed of a good euro party, that shouldn't take longer than 5-7 days.
Plus you won't need as much sp for a bard as you do for a wizard (assuming you used at least 3 elements in the wizard tree)
about the different classes themselves:As a battle bard you will be around to clean up weaker/easy opponents while buffing with mana orbit and tambours/dances making you the perfect background/support character.
You will be the life of the party
If you prefer nuking and pointing at a group of dead people saying: "see them, it was i who slayed them", then you should stay wiz, since you wont cant really kill unless opponents are 5 lvls lower or unexpecting (or you just zerk lol).