SUPPORT NEEDS:
EE is familiar and, while not perfect, it is less confusing for less-tech savvy people to use. Plus, the coaches and other skating families can help anyone who gets stuck - EMS is still new to many people, so there isn't as much informal support.
EE provides more admin abilities for the organizers, so they can help individuals who are "stuck" more easily and faster than EMS. I used those privileges a few times to assign practice ice sessions quickly and the family just had to go in and pay. Easy-peasy.
REPORTING FOR ADMINS/TREASURERS:
EMS has very good reports, one of which is a comprehensive workbook that has several useful tabs: skater registration info, event registrations, coaches, seeding, etc. It's easy to export/download this to your computer and have a variety of information in one file. As a bonus, the reports are consistent in the choice and order of fields within the spreadsheet, which allows for easy lookup or formulas.
EE offers multiple comma-delimited files that must be exported/downloaded one at a time. Opening them in Excel works, but you have to watch things like zip codes, which often lose their leading zeroes when imported as a number.
Some of the EE exports don't include the skater's USFS/LTSUSA number, which makes it difficult to match events to skaters. Fields aren't in the same order, consistently; sometimes a report will have LastName then FirstName, others are reversed.
You really have to be computer literate to make EE work for comprehensive reporting.
EVENT SETUP / REGISTRATIONS:
EE has very complex rules that must be set up correctly from the very beginning. Fortunately, we paid EE to do the setup based on our announcement, so they put the correct rules on each event. I have done this myself in the past and it's worth $25 to let EE do the work. I know it's probably easy for them, but it's worth my time. For example, a skater who self-reports that they passed Basic 4 should be able to register for Basic 4, Basic 5, Beginner, high beginner, No Test, or Pre-Preliminary free skate events.
Somehow, EMS has built those rules into their system, which is great. You do have to add every event you wish to offer at the competition and those events are gender-specific, so you have (at least) two of every lower-level event. ex: Girls Basic 5, or Boys Basic 5. If the gender is missing on LTSUSA or US Figure Skating's membership files, those events are skipped. There's no warning or error message - it took me hours to figure out that problem. (As an aside, Excel Series events have very-specific event titles and there's no merging events with both boys and girls into a single event. US Figure Skating sent out a reminder to Excel competition to make sure the events were correct. Fortunately, we only had female skaters enter the Excel events, so didn't have to do anything.
On both systems, the skaters have to self-report their highest test level, which can create difficulties for parents who don't know the correct level or have to update the highest test passed and can't figure out where that can be found in each system. (In EE, it's My Account > Personal Info; in EMS, it's appx. six "Accept / Continue" clicks along from the "Competition Registration" menu option.)
MUSIC:
EE allows skaters or coaches (or admins) to upload music for a particular skater.
I usually upload everyone's music on their behalf since I keep copies on my computer and can upload at high speed. It's a bit of nannying, but it saves skating parents time and frustration and it's pretty easy once you know how.
EMS only allows the skater to upload music, which isn't ideal. One of my parents played the music she uploaded and thought it was cut off because you only get a sample of the song online, unless you download another copy.
I submitted a feature request to allow coaches to upload. I hope they fulfill it soon because it's really a feature gap.
It would be nice if the competition event organizers could upload as well.
From the music monitors' perspectives, two told me that EE is easier for them to use. There are some system difficulties, but I didn't ask what they were.
PLANNED PROGRAM CONTENT (PPC):
Planned Program Content is a form that is required for IJS Free Skate events. The user enters the IJS program elements, in order, so that the Technical Panel has a list of items to watch during the competition performance.
EE presents a full-page form where you can pick/choose each element on screen and displays the code and the description.
For example: "Jump Combination > 2F-Double Flip > 2Lo-Double Loop" would be shown along with the other elements.
However, if you you leave something out, you have to replicate each element from the bottom-up to make room for the left-out item.
EMS displays only the codes on the full elements list for a particular program. For example: "2Lz+2T" To my mind, that shorthand can lead to some data entry errors and the need to have others make corrections later.
Adding an element, triggers multiple new screens with pull-down menus. Visually, it's more complex than EE, where everything is on one page. EMS does show both the code and the description on these "add element" screens and at a more detailed level than EE. For example, to add a combination jump, you have to start by choosing 2-jump combination or 3-jump combination. (Don't let anyone tell you there's no math in figure skating. Kidding!)
Of course, only the skater can submit PPC for EMS. I would like to see coaches and admins able to enter/submit these items.
I'm not sure if skaters can "copy" prior competition PPC to a different competition - that would be a good feature.
I use a scoring estimator app and send a screen shot to my parents, so they enter the PPC into EMS, but as with music, I wouldn't mind entering it for all my skaters in one computer session.