Greets!
I'd be a little wary of using an EG101 because I've heard it's not that brilliant at MIDI output.
Besides, if this is your first foray into making your own music, you'll probably find there's more than enough in the RM1X to keep you going for a few months at least. Or are you certain that you've heard everything it has to offer and seen everything it can do and feel that an EG101 will add to things?
You'll go through a steep learning curve, so my advice is save your cash from the EG101. Get to grips with the RM1X and, after time, you'll see areas where you could do with some new sounds or perhaps even want a new way of working. *Then* spend your money.
You may find it useful to invest in a MIDI controller keyboard to give a little more expression to your playing. Much cheaper than an EG101, too.
One final bit of advice: don't ignore pcs/macs. Whilst you can make music without 'em, you'll get a lot from the process if you use 'em.
L8Rs
JetSet