Limit for my 120 is 15 degrees, according to the POH. Never tried it in practice. Only once have I seen the "Low Fuel" caption light-up; when I deliberately sat in the hover over the pad until it came on (just to check for myself that it was working properly, as the machine was just released to service from maintenance on the fuel tank. Added 40kg of fuel and hovered until the fuel meter read 30, at which point the warning light came on).
The
R44 POH recommends landing if the low fuel light comes on, but no mention of manoeuvring limits. Even Safety Notice SN-15 (in section 10) only warns not to let the fuel quantity reduce in-flight to the extent that the "Low Fuel" caption illuminates.