Two things about baro altitiude:
- It is all relative, it only really matters how much the altitude changes. It doesn't matter if it changes from 330 to 340 or from 560 to 570. They are both up 10 meters. Any absolute altitude is basically based on GPS altitude (also inaccurate).
- It changes with the weather. That is why you can't use absolute baro altitude from one day to fly the next day.
Baro altitude is better for short term, during a flight and to hold current altitude. GPS altitude is more accurate from one day to another day, but can still vary 3 to 4 meters, so you best not use absolute altitudes that require better accuracy/precision than 4 meters.