If you still have love for your MTPG and there aren't any issues, which in my experience is quite surprising, and you bought them authorized so you'll always have the lifetime warranty, then getting the custom sleeves is not a bad route.
Keep in mind, Monster may be out of the the MTPG for replacement should you need to exercise the life time warranty; there may be a good chance you'll get something on their current line up like the Gratitude.
Or, you can sell your MTPG for around $75-$120, take that coin and with the $100+ coin you would have used to purchase the sleeve and ear impressions, you now have a lot of options to experiment and work with in the $200-300 range. This range, for me is the sweet spot.