There are many advantages to 1.7, hit delay is non-existent, bow boosting and rodding feel much smoother in my opinion, and generally 1.7 is just a better version, that's just my take on things.
Make it so you can use VapeV4 on Lunar Client 1.7. Paying for vape lite seems like a waste when you already paid 35 dollars for VapeV4, and I'd rather be able to just use VapeV4 for Lunar 1.7 than use forge and lose all the fps and mod benefits on LC.