I don't see any point NOT using the collider if you have enough cash for one good go (collider for one day). You easily level up as for each dollar earns 5x xp so level up 5x faster, meaning earning donuts 5x faster. Once brushed thru 939 the donut boxes are back then all glitches problems fixed. If you are under 939 there is always a risk with a big item like googleplex the collider or multiplier pushed you over 1 level and the rest of xp, even though supposed to level you a few times, level you only once and the rest get wasted instead.
As for the one having trouble with donuts after syncing, I'm pretty sure you aren't 939 yet. Is it because you earned level too fast? When I got more than 1 level at a time before 939, it DOES NOT get registered. It only takes 1 level, gives you one donut, then the rest is wasted after you sync (like you jumped from 105 to 108 in one shot after buying a big item. You get one donut. You sync and come back, you are at 106. I had the same trouble. A prison bus netted me over 20 levels I think and it didn't register. So ONE LEVEL AT A TIME until you hit 939 then it should be ok to buy big items.
