No other problems besides the springs being too soft which will inflect the handling of the car.
What I meant to say that trying the 300 springs are worth the effort when you can change the springs yourself (and do not have to pay other people labor). If you have to pay someone else to change the springs (because you are not able to do it yourself) it may end up being expensive when the springs ARE too soft. In that case you have to pay a second spring-change...
The only problem that may occur is that the springs are too soft and the handling of the car does not improve that much...
with a minor 600+k