You can stream samples from the SD / USB of unlimited length I think (SD or USB stick limitations apply). You are limited in terms of how the sample can be manipulated in Pd though.
@dzejsm
This answer was for the Basic Sampler patch, but the distinction of writing to/reading from an array (RAM) or the USB drive applies to any record/play a file situation:
playing a sample with readsf~ is much different than tabplay~ lets be honest
one is for sample playing surely but the other is what people usually want and the limit is around 5 seconds with tabplay~
thanks for the replies. I’ve yet to receive the organelle to test this out. 
But is there a difference between the SD card and the USB slot? I was thinking of utilizing the SD card slot to save up the usb port for external controllers.
It be really sweet if I can playback longer samples! After having bought the korg miniKP2 (before the S) was really a disappointment, not being able to loop playback of samples. well at least it can work as a one-shot.
this can be done, i explain how here , but its a bit ‘challenging’ if your not used to linux 
hopefully C&G will release an image where this is already done…
(we hoped to do this after OS 3.1 was released)
anyway for now, you can also use a USB hub to allow for more devices.
as for longer samples, basically it all comes down to what you want to do with them
recording/playing can be done direct to/from sdcard/usb of long lengths.
its limitations are you can only play/record forward in realtime e.g. no running backwards, editing, to do more than this you have to bring into memory.
also there will also be a bit of latency in triggering a sample when its coming from disk (should not be too bad though)
I will say many of these are just limitations of the externals used for direct disk playback, there is not really a technical reason that much more cannot be done off disk. but that needs a bit of C++/file system knowledge to implement.
(really surprised someone hasn’t done this for PD, is really not that hard)