If you can actually find someone willing to pay $100 for a used 6100, and can get a legit G4560 for $30, then sure you could make the switch for next to no difference in performance. Just make sure you update your BIOS first.
http://cpu.userbenchmark.com/Compare/Intel-Pentium-G4560-vs-Intel-Core-i3-6100/3892vs3511 Close, i3-6100 is faster. seems a lot of hassle to get a 5% slower pc.
ye but im savin like 60$ minimum xd for 5% performance or less tha 5%