I will do my best in answering your questions but you might want to do more research.

From what I remember the particle sizes produced by the eFlow (mesh nebulizer) vs. Monaghan Ombra /AeroEclipseXL or Sprint LC (jet nebulizers) are similar, 1-5 micron range, and 2-4 micron range respectively. The difference is that the eFlow delivers a high aerosol output. The eFlow leaves behind 1mL of saline, whereas the Ombra/AeroEclipseXL or Sprint LC leaves behind a smaller amount. The eFlow is frequently used in the CF world. eFlow has been around for quite sometime, introduced around 2006. The eFlow is also used to deliver other inhaled medications with an adapted handset (I think it's arkyiace (sp?) and others).

I guess there's a chance that the Ombra/AeroEclipseXL or Sprint LC gets deeper in the lungs but personally I have not noticed any difference with clearance. I would rather spend the time clearing than nebulizing. The quicker I can get to the clearance part the better in my book.

As to if it seems more concentrated? Well yes maybe, I have to cough within a few seconds of starting with the eFlow . I also seem to stop once or twice during to take a sip of water, catch my breath, blow my nose, etc. I do not think it is harder to tolerate than the jet nebulizer set up. Finally, pulmonary (my bronchiectasis specialist) gave it the seal of approval. I hope this is helpful!