Thank you, that's really informative. Just a question of if you think they're necessary for temporary winter tires/wheels? It can be pretty pricey to get the sensors, roughly $350+ for a set so, hence my question.
Any adverse effects besides having to check tire pressure yourself? I usually do anyway, even if the car says "OK." I've found that it won't pick up if the tires are off by 1 or 2 psi (at least that was my experience in my e90).