Hi *EspressoNewt and welcome to CS.
"Has anyone else done this?" Yes! Many snobs have started their coffee journey on a small sunbeam. I started on an EM4800C & EM0480 with krups un-pressurised baskets. The result was good and for me consistent. The espresso was nice, although there is always room for improvement ;). With the time it took to heat the milk it was lovely and glossy making art that much easier.
The reason people upgrade apart from becoming a snob, getting addicted and always wanting more are... well Iím not sure because that is what happens to most around here! ;D Ive been a snob member for just over a year and in under that time upgraded. I now own an EM6910, Mazzer SJ timer, Pullman tamper & roast my own beans. Compared to lots of snobs that would be seen as a slow progression! :-?
20kg force? What tamper are you using? Surely not the SB supplied... Perhaps you should try it on a scale and let us know. You might surprise yourself and itís less than you think.
All the best.