I've tested on S60 6680 phone (2nd Ed FP2) and both works fine:
I've used only MIDP 2.0 implementation because all recent nokia docs states to not use Nokia UI api for that,
boolean success = getDisplay().flashBacklight(500);
Iv'e got different results on Nokia SDK emulators (as you mentioned them) compared to real device: Nokia Prototype SDK 4 (S60 version) supports only backlight but no vibra, SDK S60 FP3 doesn't support any of above, SDK S60 FP2 seems to support both but no visible feedback in emulator can be observed,
boolean success = getDisplay().vibrate(500);
maybe that could be issue with phone firmware (N70), do you have a chance to test on different device from S60 family or different device of that kind?