Proxies & Protecting Yourself with P2P

I have been using circumventive methods for obtaining files for years now, but I'm sorry to report that I received my first ever Cease & Desist letter this week. :(

I believe it happened as a result of me being careless (allowing upload traffic) as well as my ISP being more nosy about P2P activity. And of course it was for content owned by that production company that starts all its programs with static on the screen (if you catch my drift).

But the question I ask you, BHW, is about protecting your visibility toward ISPs/trackers/peers.  Would high anonymous or elite proxies be useful as an obstacle for unwanted entities to discover your true IP when actively using P2P software? Would using such proxies interfere with the bandwidth allocated to you by seeding users or somehow cap your download speeds? What other tips are known for preventing your IP from being identified when leeching on P2P networks?

For the record, I made a stupid mistake that is probably the reason why I was safe for so long and only now have been served with that letter: I allowed uploading in order to increase access to more seeds. I normally never allowed this because in my experience it's sharing that gives you problems, not leeching.

I also suspect that my ISP has been capping bandwidth for users accessing P2P networks.  I noticed this when downloading something on one of these networks would cause my internet access to shift between full-speed access for approximately 2-5 minutes followed by 1-3 minutes of absolutely no available internet access -- even for plain web browsing.  This not only happened when using P2P software associated with media files, but it also happened when I was trying to download the Diablo 3 game files through Blizzard's official installation client.  It used P2P file sharing to facilitate the downloading of the large installing files (multiple GBs), and the same on/off switch of my internet access occurred.  That's why I surmised that it was my ISP's new policy to interrupt what it saw as potentially unwanted file sharing.