Never had my USB chargers burnt before *touch wood*
Was using 2 x MR3020+E398 24x7 ever since I bought the the modem from blacktubi. I've supposed it's more than a year now.
One thing to note about using high power 3G/4G modem with MR3020. The power supplied via USB might not be sufficient, make sure you're using a decent USB charger (i'm using one that can supply at least 2A) or you can supply additional power via a self-powered USB hub or the Y-cable.

Just want to share one of the best USB wall charger that I've come across so far - PortaPow Quad USB
Main features that I like about it:
- Quad USB (a bit bulky but i don't mind )
- Auto lower individual USB power to the minimum if device is fully charged (with LED indicator)
- 3 Years warranty (not that it will be easier for us to claim since it's based in UK )
You can buy one from eBay at around RM70.

For WR710N, I'm using one running on ROOter. Bought two and still undecided what to use with the remaining one. There are a couple of sellers selling it here. Just need to do a quick search in Networking Related Items.

This post has been edited by maxcheam: Oct 31 2013, 04:16 PM

3.5A might be overkill. Use it carefully as it might kill the device that can't take that much.

If you want more power, check out this monster 5A charger from the same company - PortaPow PowerStar

This post has been edited by maxcheam: Oct 31 2013, 04:19 PM