Expect the worse. Deliberately left 30% of the luggage behind in Jeddah because the plane was overweight. No Eid gifts for the family. Part of the luggage arrived in Islamabad after my return and was picked up by my family. Part of my luggage still missing more than 3 weeks after my journey. Customer service unresponsive and has no clue how to deal with the situation. The lower fare definitely not worth the hassle...
"Group" tickets: The price of the tickets for lowcost flights increases with the number of tickets sold. So it may happen that there is only one ticket left at the lowest price (e.g. 30Euro) and that the others cost more (e.g. 40Euro). If you buy two tickets, you will be paying the higher price multiplied by the number of passengers (in our case 40*2=80Euro, instead of 30+40=70Euro). Always check that the total price for the group is not higher than the initial price per person multiplied by the number of people in your group.