All the User Style slots on the PSRs have a limited amount of memory available; e.g., there is a point where a style's size will be so large that you will get a memory error if you try to load it.
The PSR-630/730 have a smaller memory for styles than the PSR-8000. Many PSR-8000 styles are 39k or as large as 59k that I have run into. They have two introductions and two endings that the user can choose from.
The smaller 730/630 ususally uses single intro/ending styles of up to around 20k for each user slot.
You CAN use the larger 8000 styles on the smaller machines. What you need to do is force a memory exceeded error into the user slots by trying to load the larger style into each of the available memories one at a time. Each time you get a memory error for a given slot you are clearing that slot of the memory that it was using. When you have cleared sufficient slots of memory the large style will then load.
For example, I use a PSR-630 with 4 available slots. If I have each slot filled with a "regular style" I will have around 20k in each slot. I try to load a 59k 2 intro/ending PSR-8000 style into my user slot #4. I get a memory error (and clear the 20k from that slot). I then try to load the 59k style into slot #3, then #2, and always I will be able to then load even the largest style into #1. Many times you only need to clear one or two slots. I can then load other large styles using the same slot that was previously filled with a large style without having to go thru this clearing procedure (so long as I don't also try to load up the clear slots too).
I can then access the two intro/endings, even though the PSR630 doesn't have a button for selecting these. As noted by my friend Carlos Rodrigues in Portugal, when you go from Main A to Intro and from Main B to Intro you will hear the different intros of these larger PSR-8000 styles (same with A to end and B to End for hearing the two different endings).
This may prove to be a very important technique when the new PSR-x40s are in circulation. If the new synths user more memory for their styles, presuming the style format isn't fundamentally different, this same technique will work to access the new x40 styles into the older 630/730s.