The only time I've seen Moodle require less is when it starts to fade ... meaning, teachers choose to use something else and if that something else is perceived as being better, then usage declines.
Sounds like, however, in your brief description of usage ... "under 200 students for now" means there are aspirations that the number of students will increase ... usage will increase ... and, depending upon course content (like a Digital Photography Class - a DPC) and how courses are designed (DPC, for example, has one assignment for students to take 6 photos with 6 different lense settings/exposures and submit them all. Each photo somewhere between 1.5Meg and higher ... probably no higher than 2Meg. Do the math on that one assignment. Usage increase will require more ... maybe more space ... maybe more memory ... maybe, maybe.
See what I mean?
You've already been in a situation where there wasn't enough resources. Now the 'game' is guessing just how much more of space/memory etc. Moodle require in relationship to the cost.
Folks could give you specs and numbers, but ....
You've already determined the next package up ... the 2Gig ... sounds underpowered. I would agree. But, are you willing to pay for resources not used right now?
Uhhhh ... I'd be cautious about the "Softaculous Included (for moodle updating)" ... that may not mean what you think it means - or want it to mean.
Ok ... if ya want numbers ... this isn't a large site: All in one server ... apache, mysql on same server ... same IP.
16Gig Mem (which is aleady using SWAP space and needs tunning), 7238 rows in mdl_user table ... = about 7,238 users in the system. Has a 1 TB data drive for moodle data (57% usage and grows) ... been in use for 2 years now ... heavily used for the HS students who are in AP classes ... but mostly for quiz. There are courses for say one AP course that has 4 teachers and their students (sorta team taught online). Has that DPC example course mentioned above and it's backup is over 50 Gig. The DB connections variable for MySQL has had to be increase to over 400 - 401 to be exact ... simultaneous connections ... not necessarily to the site, but something by a user in the system using the DB.
Am not bragging on it ... just trying to give you an idea of perhaps researching a little more about usage so you can make a more intelligent decision - but caution you to leave wiggle room ... upwards!
'spirit of sharing', Ken