Seat reservation on Hikari?

Two of us are traveling from Odawara to Kyoto on Hikari Shinkansen 519 on Wednesday, 14th November at 4:08pm. At this time, is it recommended to do a seat reservation, or do you think it'll be fine to get a seat in the unreserved cars?

Hikari Shinkansen 519 on Wednesday, 14th November at 4:08pm. At this time, is it recommended to do a seat reservation

At this time, Cyberstation
http://www1.jr.cyberstation.ne.jp/csws/Vacancy.do
tells there are many vacant (reserved) seats in Hikari 519 which means you will have chance to get the non-reserved seats. But I strongly recommend you to reserve seats, since it is only 530 yen more expensive (reserved seat fee 5070 yen, non-reserved seat fee 4540 yen) and it will take about 2 hours. Of course if you have the Japan Rail Pass you don't need to pay for the reservation.

which means you will have chance to get the non-reserved seats.

No; vacancy in the seats which can be reserved does not show your chance to secure a non-reserved seat.

You will travel on a normal weekday,
and many trains (including all the Nozomi trains) skip Odawara Station.
I suppose you can reserve your seats just after coming to Japan.

In Ordinary-Class cars, five seats are in one row.
When the train goes westbound,
three seats (A to C) are on the left side (i.e. seaside)
and two seats (D and E) are on the right side (i.e. mountainside).
Seats A and B | B and C | D and E in one same row are next to each other.

The Hikari 519 (Odawara 16:08 -- 18:11 Kyoto)
will not have smoking seats.
The train will make a stop at Kyoto just briefly, for one or a few minutes.

Enjoy your trips!