I would, if I wanted to visit 3 parks in one day, and in a tight time schedule to boot! You should be able to buy an ILL$ for Remy, but
Genie+ will be the only way for you to know when you could ride TS and Safari.
Since you’re starting in Epcot, I’d buy the Remy ILL$ first, since you can choose your time. Then you’ll need to monitor the LL times for both TS and Safari in order to get ones that fit your schedule. Even if you just book a LL for TS and then plan standby for Safari (because your desired LL time for Safari is reached and passed before your desired TS time is reached), you’ll have much more control and confidence in being successful with your plan.