I checked, and there is a noticable difference between 0% and 100%.
I guess it is not a spoiler to describe this observation, but rather a needful comment for the further discussion.
The k-factor (spellpower), the magic ways rank and its associated stat indeed each have some impact on the spells outcome, that is one or several of the observables: casting time, range, area of effect, inflicted damage, relative strength of a buff, chances to fumble, mana costs and duration over time. However, most or all of these are restricted to certain intervals, such that increasing the training ranks, stats or k-factor does not change anything for that observable when the combination of the three quantities is sufficient to reach a certain limit. Thus, spell power may be of great use to compensate for a certain lack of training or a debuff (curse) at the cost of higher mana drain, casting times and chances to fumble, while in other cases, it will only improve some minor aspect of a spell. Also, I have the feeling that the relevant ranges are wider for those spells of the higher realms.
About my statement that magic is not balanced well with the combat arts, I should specify that this mainly holds for superior mobs (anything that can defeat a player character with one double hit, but not vice versa), and that I assume this to improve greatly when other changes will be made, for instance in mob behavior (retreating, jumping or even casting back), mana supplies, available equipment (use of crafted shields and armor) or mount mechanics (chances to miss or fumble while riding). Conclusion: I am happy with the new rules for the spell system and looking forward to observing further fine tuning.
