For people with smaller stakes, who don't use or IIRC don't even see the vote power slider, voting more than 10x per day would result in a lot of 'dead votes'.

I'd suggest making the change to blockchain as proposed but then offering an UI option, ideally as default, where vote power would automatically be scaled to mana percentage, which would replicate the earlier behavior at the UI level. Power users who want to "use all their vote power" and/or manually control vote power for whatever reasons would disable that option.