A couple of thoughts for you.
1. Only you can determine if it is worth spending $850 on an upgrade.
2. Your $850 price might be a little low. You may need longer steering cables (I did). Mine were about $250 a pop for Morse cables.
3. If you go with a jack plate, I would highly recommend an aftermarket bearing carrier because a surface piercing prop puts a lot of strain on your lower unit.
4. It looks like you have a nose cone / low water pick up. If not, this is mandatory.
Don't expect phenominal gains. The plate will help a lot, but my guess is you will see an increase of 5 mph, tops.
One last thing.......if you run a jack plate, you absolutely, positively need a water pressure guage. Never run your motor at less than 10lbs of pressure. I run mine between 12 and 15 lbs.
Good Luck.