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And for the bed, do you thing it would be better to change RT1 to 4.7 K ?
Maybe this answers your question: [reprap.org] 4K7 is pretty ideal for beds, 1K is close to ideal for extruders. The lower the resistor value, the higher the temperature of the area with the highest resolution. Higher resolution means better accuracy of the measurements.
If you wonder why there isn't a 1K resistor by default: only very few people take the efforts to make their own thermistor table, so such a change would confuse people more than it would help.