Like many people here, I am a long-time asthmatic as well as having bronchiectasis. The switch to (generic) Symbicort was made because my asthma is not well-controlled by Levalbuterol alone. It is the current protocol for managing moderately severe asthma, and ca long-acting beta-agonist or LABA and an inhaled corticosteroid or ICS. The formoterol in Symbicort opens the airways and the budesonide is an anti-inflammatory. There are other formulations out there - this is the one my pulmonologist prefers, and it works for me.
Albuterol and Levalbuterol are both short-acting beta-agonists (SABA) meant to immediately open airways, but do not long-lasting effects.
The other advantage is that it is an inhaler, so you use it & wait, then neb only the saline. Also, if I am in an exacerbation (very rare for me now) I do neb either Levalbuterol or DuoNeb before saline.

Now, the Pari eRapid flow - YES it is pricy - mine was about $725 from Nebology after discounts they applied, and Medicare will not cover it for most people. I was very fortunate to have some $$ and a husband who encouraged me to get one. We travel a lot - often in a 13' camper, or living out of a fairly small suitcase, so the compact size is very important.

I have made a new discovery since I got it - during allergy seasons (usually late July - Sept) I often wake up choking, but if I neb before bed and do some clearance, it doesn't happen. In fact, I'm my deep breathing while I type and stopping to huff cough🤧