Bass sounds,some strings,ethno-world sounds etc....There are many sounds from SRX but you will never find them if you look for SRX sign in the name.There is just Koto SRX and Koto SRX Bndr which are the same with SRX in the name,maybe there are some other sound but....There are many sounds from SRX inside FG but you must look for them.The best way to do that is to go to the
http://www.rolandus.com/experience/interactive_demos/ and then try to find some patches from DEMOS inside FG.
That is the best way to do this.Or perhaps if you have Fantom X with all those SRX's inside.Sometimes there are just patches that are mixed inside SRX.And that kind of mix is not in the FG but if you know what voices are mixed inside SRX that you can make exact copy of that sound in the FG or maybe better.For example : There is one sound in the world collection named Yuehchin+ and that sound does not exists inside FG.But if you mix Shamisen sound with 485 Clr My Gtr A and maybe some Koto C sound then you will have maybe even better sound on the FG.
FG is so good when it comes to internal Wave ROM and because of that your song can sound even better in the FG.
SRX is not that good comparing to the FG.For me it is better to have Fantom G with ARX01 and maybe some other ARX that will be released in the future or maybe with Brass or EP then Fantom X with 4 SRX's.because Fantom G have superior INTERNAL ROM.And this ROM is much better then Fantom X.