I love this mode too but unfortunately 20 is so Glitchy for me on android that I get super frustrated with it. Best I've been able to do is like 200k in a round. Hoping they get these bugs worked out soon
Imo keepers suck and they cost way too much to upgrade. I think they play like 3 star players too. To answer your question though, I don't think it really matters. You'll use them for a month tops and then move on to much better players that you can max out for a fraction of the cost.
Had the same issue last year. Ended up losing a 120k team early in the year. I got locked out completely. Customer service will tell you are only allowed one account per device. If you want to run 2 teams with no problems you'll need a second device.
I should be getting the vip invite soon. Been grinding since the beginning and spending the money. Hopefully they'll reward me for it soon since we only got a handful of months left to play this version.