1. If this is for a single house, go for soldered joints.
2. If you are a business moving in to plumbing, then:
2a. For commercial work, press fit probably makes economic sense.
2b. For domestic new installation work, it's probably 50:50
2c. For domestic maintenance, go for soldered joints. But if the installation was made with press fit, you can't solder within a short distance (450 mm?) of a press fitted joint.
3. Are you sure you mean press fit or push fit? Huge difference.
4. Press fit requires a special tool, a set of tongs for each size, and must generally be calibrated every so often. Equipment will be £1,000 to £1,500.
5. Press fit fittings are expensive.