Twixtor Pro has more options and can do a better job, especially when you want to slow down footage. Pixel motion calculates the movement of the pixels and does a really good job of figuring out where the edge detail should be in the blended frames. For most shots, Pixel Motion is the best option. After Effects and Premiere Pro have virtually identical frame blending options.

If you need to keep real-time in the original clip then you don't change the frame rate, you pick the best frame blending method. If your AE comp or your sequence is 29.97, which is the broadcast standard for all countries that use 60Hz power, then changing the frame rate of 25 fps footage to 29.97 fps (or 30 if you want) just means that 30 seconds of real-time will now playback in 25 seconds. If you want to keep every original frame then all you have to do is change frame rate interpretation of the 25 fps footage to the frame rate of the sequence (Premiere Pro) or the Comp (AE). When you talk about 25 fps footage and a 29.97 fps vs 30 fps I assume that you are trying to avoid any frame blending or minimize any frame blending problems.

You would use Pixel Motion Blur or Force Motion Blur to perfect the clip. Frame blending will not do much if you want to speed up the motion. The only thing you might want to do when you increase the frame rate of a clip is to increase the motion blur. In this case, every other frame will be used. Increase from 24 fps to 48 fps and 10 seconds of realtime becomes 5 seconds of screen time.

Increasing the frame rate speeds up footage. I'm sorry but I don't understand what you want to do.

Twixtor slow motion premiere pro