If you learn to use your guitar to make the noises that aren't there, you'll be a better guitarist. If you use your money to buy machines that make the noises that aren't there, you'll end up with a lot of machines. My students say I'm kind of confusing when I say things like that.
First things first is a long clean delay, surely the POD will. You DON'T want modulation, warble, you want to HEAR everything so you can duplicate with exactitude. Learn every lick you like in at least two places with different picking patterns, notes-per-string etc. (four places is better, EVERY place is... the goal). REAL speed comes from giving an EVEN value of time or length to every note in a lick - you can put an amazing amount of crank on one single lick in one place with enough repetition, but NOTHING about it will apply anywhere else as soon as you leave that exact pattern.
If you use a looper or recorder to make backing tracks instead of using backing tracks, you learn how to play rhythm guitar. Drum machines are so cheap/free with everything, and they're more interesting than metronomes. But don't mask mistakes, that's backwards - when you skip over a hard, uncomfortable part, you're building a pattern of defeat.
http://www.drumbot.com/projects/sequence/
Hands down the single best tool is a $1.29 notebook & pencils & erasers. Human brains are not, actually, that good at remembering EVERYTHING AT ONCE. Write down the dumb stuff so your brain has room to work on the good stuff. Can you play five notes over the space of four? Four over seven? You can't until you try, and you can't try just by laying around thinking - you HAVE to write out all those kinds of experiments. There's HUNDREDS of chord & scale superimpositions. This isn't music paper, this is just PAPER paper.