As an experiment, I have moved to JT65 on 10m today. I was getting JT65 spots on 6m until just before QSYing about 40 minutes ago including some night-time Es. As yet, nothing reported on 10m JT. I think my antenna is not as good on 10m as my vertical V2000 is on 6m, but the cable loss is lower.I suspect my ERP on 10m is a bit lower.
UPDATE 1325z: Although my 10m JT65 has been received in southern Europe by 10m Es, I have had fewer spots than on 6m. There could be several reasons. Firstly the antenna may not be as efficient and the ERP may be far less than on 6m. Secondly, Es may be reducing in quantity now we are getting later in the season. Thirdly, there could be fewer people monitoring on 10m JT65 than on 6m JT65. I expect it is a combination of all three.
UPDATE 1726z: A couple of South Americas spotted on 10m JT65. Best DX so far is PY5EJ (9889km). So far, my own signals have not been spotted in South America. This may have been Es but I suspect it was either F2 or a combination of Es and F2. As this is a N-S path there could be equatorial spread-F involved. I am no propagation expert, so I welcome inputs from others who have better knowledge.
UPDATE 2016z: With just 6 Es spots on 10m JT65 all day and not a single spot from any G stations, I suspect there are fewer stations on 10m JT65 than 6m JT65. The bonus was a couple of spots of South Americans although the day passed (so far at least) without my own 10m JT65 signal being spotted outside Europe. I shall be on 10m JT65 again tomorrow.