I agree with figment. It depends. DLR does enforce FP return times, so gone are the days of yore in which you could grab FP after FP and not use them during your FP window, but use them later in the day when you felt like it.
Going to EMH/MM is WORTH IT! Most of DL visitors are locals. So on weekends, they will tend to show up late morning and they stick around all day and all evening long. During the week, the locals will tend to show up late afternoon/early evening when they get off of work...they'll have dinner at the parks, go on a couple of rides, see fireworks and/or a parade, and go home. Sometimes, if there is a new attraction that's debuted or if it's an attraction that's just come off of being refurbished, locals will go to DL for the evening with the one sole purpose of going on that single ride, and they'll be willing to wait in line for a couple of hours in order to do so.
Park hopping:
It is VERY easy at DLR. Given average crowds, probably 10 min max (but more like 5 min) from DL Town Square, exit DL, walk across the Esplanade, show your ticket at the gate, and go through the turnstiles into DCA. I have found that the locals are usually more in love with DL than DCA, so if it's really busy at DL, it's very convenient to hop over to DCA where crowds might be a little lighter.
Everything is more compact:
DL's Fantasyland is a good example of this and it's why getting up early and getting to rope drop is so advantageous at DLR. You could end up going on 6-7 rides in that first hour alone.
Peter Pan doesn't have FP, btw. Also, at DL, Winnie the Pooh almost never has a line and if it does, it moves very quickly. I have found that the first 3 hours that the parks are open are the golden hours with lower crowds, lower wait times, etc.
How many people are in your group? Any kids? If so, what ages? What are your family's favorites at WDW? Are you thrill ride people or do you have anybody in your group who would just hurl if you took them on Thunder Mountain Railroad? Does anybody have disabilities requiring a scooter or wheelchair or a disabled card (autism, for example)?
Also, what dates are you thinking of going? Will you be staying within easy walking distance of the main gate or staying farther away and driving to the parks? In other words, are you thinking of taking a midafternoon break or just soldier through all day?