The PSR-I455 would be very similar in many respects to the PSR-E413 you have now, as it's based on the PSR-E433, which is an updated version of the PSR-E413-- so it will have more voices and styles than your current keyboard, as well as a few more functionalities such as tabla/tanpura patterns, twice as many registration buttons and memories, the ability to use a USB flash drive, the ability to convert user song recordings to standard MIDI files, and the ability to save and load user backup files without having to be connected to a computer. You would probably find the transition to be easier than if you switched to a different brand. But if there are certain things you don't like about the PSR-E413, it's possible that you'll have the same complaints about the PSR-I455, unless they're things that were updated.
On the other hand, going with one of the Roland models would be a more dramatic change, which could be either good or bad depending on what you like. I don't have any experience with any Roland models, so I can't give you an opinion of them, and anything I said about them would be something you could determine for yourself by looking at their manuals and specifications.
One alternative to the models you mentioned might be the PSR-E453 or PSR-EW400, which are basically the same as each other except that the PSR-EW400 has 76 keys, stronger amplification, and line out audio jacks in addition to the headphones jack. They have a little better polyphony than the PSR-I455, 48 notes at once versus 32, and more voices, although the PSR-I455 might have more voices and styles which are focused on Indian music, as well as tabla/tanpura patterns rather than DJ patterns. The PSR-E453 or PSR-EW400 would also have USB audio for more convenient audio recording on a computer. From what I've seen on some of the web sites for online stores, the PSR-I455 is usually much more expensive than the other PSR-E4xx models, which I suppose is because it's aimed at more of a localized market and hence fewer units may have been manufactured.
