Official comment
@Egor > Congrats on the purchase of the XDJ-RX! Let me try and answer your questions...
1) This is perfectly normal - stutter cue is how DJs used to find the beat to cue their player before vinyl "scrub cue" was created on CDJs. I find myself using the stutter cue from time to time as it's how I started DJing and I find it's sometimes more accurate than scrubbing!
2) The 4 beat function is outlined in the manual (pg. 16 of the English version), and you will actually get a maximum of 4 seconds of reverse slip due to the limitation of the memory buffer.
3) This is not a bug but rather the way the engineers have coded the player; we've asked them to improve this to function in the way that you're asking for it to work - by extending without starting the loop over from the in-point, hopefully we'll see this in a future update.
Thanks for your comments and please let us know if you have any other questions!