Both are excellent radios.
On the Sherwood tests the FT-710 came 4th, which is very good. It is disappointing Yaesu has chosen to, effectively, ignore the QRP market it once dominated. It is almost as if Yaesu has given up.
The FT818 was really about component obsolescence and really had none of the features expected in a modern QRP rig. To many, it was a total disappointment.
Yaesu introduced the FT-710 which is SDR based. Personally, I found the ergonomics easier than on the IC-705. The FT-710 includes 4m, but does not do 2m and 70cm which I missed. It also has an auto-ATU.
ICOM launched the IC-705 some years ago. It is a 10W portable unit covering 160m-70cms, all modes, but it omits 4m and the auto ATU. It is also too expensive. Having tried 4m both in the Es season and before, 4m has proved a disappointment. Personally, I was expecting more from the band.
In the end, I went back to the IC-705 as I missed 2m and 70cm more than I missed 4m and the auto-ATU. It is a 10W radio and far smaller. As a QRPer, 10W is quite enough, especially on FT8 and WSPR. On its battery it is a 5W radio. Had Yaesu announced a new QRP rig, I might have traded my FT-710 in for one. Sadly, I see no new QRP rigs from Yaesu on the horizon.
Personally, I give Yaesu a maximum of 36 months in the amateur radio business.
As a Yaesu fan of old, I very much hope I am wrong. They have had chances and blown them. To my mind, they are a company floundering.