Are there any issues with connecting speaker wire in this manner?

Ozzy---the largest diameter niobium wire I found is 14 gauge.  I was planning on getting runs twice the length I need and wrapping the amp binding post with the mid-point and then running both ends out to the speakers.  I don't want to use separate wires at the amp end as I'm concerned about stripping the threads on the amp binding posts.  I did this already once and don't want a repeat.

Better to use 12GA stranded copper, single conductor for each polarity. Go to Lowes or Home Deport and get 12GA stranded copper THHN from Smithwire. Cheap and pretty darn good.

The advantage of banana plugs (as others have suggested) is that they are much easier to manage and connect to the terminals... and... eliminate the possibility of damaging the terminal connection inside the amp (if the terminals rotate as you tighten them - which I've done before).  I switched to banana plugs to avoid damaging the terminal connections inside the amp by overtightening the lugs on the outside as I fastened spades or wire to them.  

The other caution is that you can very easily short out / damage your speakers if you accidently touch the positive and negative wires together when you are fastening the cable to the the speakers, or amp - if you attempt to connect them while the amp is on... or... if a strand of wire from one side touches the other wire or terminal.  Of course, making sure the amp is off when you make your connections and that you have no stray strands touching the other wire / terminal, helps to avoid this.  And, using bananas is much easier to make the connections and avoid any shorts.  

You also may want to "tin" the end of the wires for each channel with solder, which can also make the wires easier to connect and help to avoid "stray strands."    

It’s not very effective ,their is a science to cable construction ,dielectric ,and connection silver or gold over Copper connection with quality solder or Furutech type screw down terminals , if it were that simple everyone would be doing it .

look at Wireworld Eclipse it is a very good cost effective Loudspeaker wire that addresses everythung from best in class Dielectric, Wire purity Geometry, and connector  type at a reasonable cost ,  it depends how far you want to go .

if you want lower price blue jeans cables for entry level wires.

I believe audioquest type 4 used twisted solid core wires of various sizes in their construction. It was an award winning cable and still popular today. I love mine.