Just upgraded my speakers - do I still need the subs

Keep the subs. After trying subs on your next floorstanders THEN decide if want to sell.

Yes, keep them.

I also have the Ref 1 with KC62.  In my med/small room, with optimal speaker placement, I prefer the sound with the sub, but I would not call it a significant improvement. The Ref 1 are pretty good in the lower range. 

Yes, there is no way a 6.5" driver can produce real low bass even with the help of a port (I don’t like ports). Lack of low bass, makes this speaker size sound very clean, impressive, some makers like KEF do an amazing job at that, but ....

Keep the subs, and get thee a SPL Meter, inexpensive ones work well to blend the Sub with the KEFs.

This one has a tripod mount on the bottom, so you can position it on a tripod at seated ear level, and get hands free vibration free readings.

https://www.amazon.com/Digital-Decibels-Battery-Indicators-Factories/dp/B0DQKP4LDV?psc=1&ref_=sspa_dk_detail_gen_ai_1&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM=

I use this test disk with 29 test tone frequencies, tracks 9-38

https://www.discogs.com/release/7290000-Various-Amazing-Bytes

Expensive, I bet I could help you find an inexpensive copy, I keep asking for suggestions of test disks from members here, no one suggested anything yet. Use a CD, not an LP.

Using the SPL, make sure your system is balanced L/R before you set them up with the subs. My friend is having a devil of a time with a weak right side, using his preamp’s balance control to listen now, but....

You can download test tones here Source: Hsu Research https://share.google/et8a6EKJnUpEbnrRL