Hello Fantasyvn. The answer is yes, and no! Some styles will sound just as they sounded on your old keyboard, others will need adjustments in volume and such to sound OK on your new keyboard so called "tweaking." Some may even lack some voices, because the new keyboard will not have these voices. If you look at the styles section here on PSR Tutorial you will see a lot of style conversions, for instance Tyros 5 styles converted for S950. Many members here are experts at adjusting styles so they can be used on other models! When you get your SX700, try out your old styles on it. If they don't sound as good as they did on your old keyboard, look for styles converted for the SX700, or adjust them yourself on the keyboard, or by using a computer program.
New models have better speakers, so most of the styles will sound better because of that. BUT many of us - me included- actually thought my old keyboard sounded better. It takes some time to adjust yourself to the new sounds of a new keyboard. All the best from Toril