I'm really happy to see that you added the Akai to your list!
I recently, after much difficulty-but that's another story, purchased the DPS24. I did a lot of research prior to choosing it and I'm extremely happy. I'm upgrading from
a Yamaha AW2816 which I purchased because I didn't think I could afford the DPS24. I found the Yamaha to be functional, but not user friendly with a confusing and unintuitive UI. The DPS24, on the other hand has an elegant UI, a well laid out and intuitive panel, lots of inputs, great preamps, amazing sound and, most important, excellent support. Akai has continued to upgrade and enhance the OS, adding features and adding value to an already great machine.
The other thing I stress to people considering this machine is just how great their user forum is. Not only are there some great musicians there, but they are just incredibly helpful, generous and nice. Answers to virtually any question you might have are quickly given and people from Akai also frequent the forum to give the official line on things. All-in-all, it's a great resource and was an important plus as far as I was concerned.
Another thing, there are a number of users who have switched from Roland to the Akai and all of them acknowledge that the DPS24 sounds considerably better than the Roland boxes.
There are a number of other plusses to the DPS24. If you have questions, I'll be happy to answer them as best I can. I'm still learning my way around it.
I would strongly suggest that you spend some time browsing Akai's web site at
www.akaipro.com and sign up on the user forum and ask any questions you might have from REAL experts. No matter what choice you make, these people will be polite and helpful and HONEST! There are a number of forums. The main one is, of course, the DPS24. Find it
HERE
I don't have any first hand knowledge of Roland's recorders only 30 years of using their keyboards and other gear and uniformly finding it frustrating, poorly documented (the DPS24 doesn't have a great manual, but all the basic information is there) and usually hampered by some oversight in design. I've sworn off Roland gear because of this.
To be fair there is one area where the DPS24 is somewhat lacking-effects. The basic complement are there and they're adequate, but not earthshaking. The unit does have 4 insert points for patching in outboard gear and what a lot of people are doing is flying tracks out the ADAT interface and into their computers to use VST or DX plug-ins. It's possible with the optional ADAT board to transfer 24 tracks at a time in this manner and some people have successfully done this in REAL TIME! They call it frankenstein!

search for it on the board or in the Console forum.
The other problem is that these units are in VERY short supply right now. Akai is coming out with a newer version which, according to reports is identical except for a color change, but they've delayed production several times and the rumor is that they are going to make some changes. In the meantime, they've released a small quantity of the original units to try to fill back-orders. I purchased mine used on e-bay which is another option. Numark has recently become new US distributor for Akai Professional products so that might be a factor in the delay as well.
I hope all of this is helpful to you.
Ted