Yes, you are basically playing with 99 gear except you do have some potential options for HC citadel, you get a legendary, and some enchants scale a little bit better. But I will also say that 101 boe gear and HC gear compliment it really well, and my 99 has a heck of time soloing old content, doing better damage than my 101 due to difficulty of getting said gear, and overall missing some options that increase the strength of my 101 warrior by a bit. Basically you get a bit more options at 100 and accessibility to what you already get at 99. If I remember right you can get essences at 101 although very slowly unless they changed that.
[doublepost=1548815537,1548815444][/doublepost]You generally don't want WoD because you can't enchant the gear, most enchants stop at 136 ilvl which is roughly the lvl that SoO is at. If the enchant and the gems don't work in tandem, heck its just better to go with legion gear.
[doublepost=1548815757][/doublepost]As I was saying before, its also not always SoO gear, don't see much beating the stone of the elements or my Gurths. It really depends on the stats and the effect. Oh, you also get access to the last talent that could complete/help your class.
[doublepost=1548817379][/doublepost]I will also add that it is much more difficult to go through HC citadel now below 110, as you are much much weaker than you were in legion in terms of PvE. I rushed and was able to get the gear(although non-socketed) I needed before legion was over but now your best best would be getting a 120 to run you through it or having a second account with a 110+ to get you through.