I actually just returned from WDW today using Delta Express from Logan. When I departed Logan on July 19, the airport was actually pretty quiet (I was on a 12:40PM flight). Using the e-ticket kiosk, I was all checked in within 10 minutes. Security only took 5 minutes after that. The lines did seem longer when I returned to Logan this morning, but nowheres near the lines that existed earlier in the year.
If you have e-tickets, the kiosk is a huge time saver, you just walk up, swipe your credit card, answer the questions, tell them how many bags you are checking, and the kiosk prints out your boarding pass. Then you take the bags to the dedicated Delta counter next to the kiosk (no lines) to have them put the tags on and take the bags. The kiosk is one stop shopping, no curbside checkin needed (although it is available), and no rechecking in at the gate (which you would have to do if you use curbside).
If you are flying at 9AM, I think the airport will be a little bit busier, but should not be unreasonable. I last flew in December and noticed a significant improvement in the speed of security. The National Guardsmen with the big guns are no longer at the airport although you will still see State Police around. Security has now been taken over by the Federal employees, so I think they are a little more thorough, but not to the point of inconvenience, as the staffing levels also seem to have grown. Random gate searches are still being conducted, but I didn't get picked this time (which is unusual considering that I travel alone which often flags me for the search).
Here are some tips I can give you, allow some time for the Boston traffic, even early in the morning. Read the directional signs carefully at the airport, there is a lot of construction going on outside Terminal C (where all Delta flights now originate) and some traffic has been rerouted (but changes are marked well). Be prepared to show your ID three times (once at baggage check in, once at security, and once upon boarding the plane). Keeping the ID's out with your tickets will help speed up the process. Use the kiosks if you can, as ticket counter lines continue to be long, especially in the morning. One final note, depending on the gate your flight leaves from, food options beyond security are extremely limited, so you might want to keep that in mind (there is a Burger King in the concourse).