Ya, I'm uncertain as well. Though I'm fairly certain the Original mode in DXC is untouched gameplay wise. I do wonder how it plays performance wise though.
here is a rundown of the psp port vs the orig pcengine version (taken from
http://www.vgmuseum.com/mrp/screen-cvrob.htm)
Sony PSP: Disappointing to some is that the PSP version of Rondo, as unlocked through the playing of The Dracula X Chronicles, is not a fully faithful port. You'll first notice this when the title screen pops up and you're greeted by new voice acting (German, still, but now featuring English subtitles), a localized logo (Castlevania: Rondo of Blood), and two start-screen options--the new addition a "Quit" option that returns you to Dracula X Chronicles' title screen.
The menus, too, have been redone in English, and the cut-scenes' voice acting has been re-recorded to match those found in the remade Rondo and the tweaked Symphony of the Night, which have also been re-acted by the very same voice talent. Richter and Maria's voice samples have been changed to English to reflect this; too, some enemy cries and sound effects have been swapped for newer samples. The in-game start menu has been changed and now includes the option "Quick Save," which allows you to save your progress at any time and resume right from the very same position upon continuing.
One glaring change is faulty sound emulation, which results in stage themes ending and restarting rather than looping plus cut-scenes that don't synch with either the music or voice acting.