i am using seedbox solutions for some months, now. They work perfectly fine with private trackers. The only issue I find is that with some trackers the upload is really fast, while other trackers barely upload anything. I dont know what is the reason, can be the trackers themselves.
Another thing I dont like is their RUtorrent software. Some trackers require you to have a max. ratio per torrent, i.e. 8. While RU torrent has some way to control the ratio for each individual tracker, this option is disabled in SS. I wrote the staff for a solution and they never replied.
However, the balance price/quality is decent, it is the cheapest offer in the market for a shared 250GB slot (around 4 euros per month). So no complaints. I reccomend this for an entry-level sharer.