+1 … great reply !
and welcome 
my 2c:
I guess you can improve the SLO, but there will always be underlying deficiencies:
In particular:
Stiffness - SLO’s Joint are all MUCH lower tolerances to Proper Stridas - so by comparison they feel Floppy and loose. The heavier you are the more noticeable this is. thats fit of handlebars, QR.s steering pin, rear joint etc.
You may be able to tension the belt and MOST importantly adjust the snubber to ~0.25mm clearance, but many SLO’s have narrow snubber bearings - in which case the bearing will slice the belt like a pizza cutter !
Strength - if you are over 80Kg and strong - look out for cracks - un-heatreated, and poor quality Aluminium looks much the same as the proper tubing - it may look similar, but dont be fooled that is IS the same ! … do you think the SLO maker gives a stuff about the long term strength and stiffness, and in fact anything long term ??
With your eye’s open an SLO an intro to the Strida ‘concept’ - but to think of an SLO as a better value Strida is just wishfull thinking 
Whatever - enjoy the Bike - riding the strida is not only fun, good for your back, and its roll-when folded ‘stick shape’ goes in many places other suitcase sized shapes dont - You will meet a lot of folk … as someone else said "owning a Strida is much the same as owning a cute puppy - everyone loves it "