Unfortunately, it is. If you want to try a different client, I've heard good things about qBitTorrent.
Is it a valid client on trackers ?
It is indeed allowed at most of trackers. I used it on PTP,TL,M-V,what without any problem. but on of desi tracker banned it so i had to switch back to ut 1.6.1 (which i believe is lightest yet fully functional client ever existed)
not sure if it's of any help but i keep using utorrent 1.8.5. works fine.
Almost exactly the same with me I use utorrent 1.8.4 . It has a tiny footprint when running, is accepted by the trackers that I (still) use and is stable and not bloated by unneeded software built into it.