I think getting on Poloniex would be better.
maybe but going on yobit first is not a bad idea
I think for low volume coins it is actually a detriment to be on too many exchanges as it just spreads that low volume around which makes the volume at one exchange look even worse.
Yobit is not any improvement over Cryptopia so I think that 0.5BTC would be wasted.
You are thinking that there is only a limited number of users, and they will make a choice of Cryptopia or Yobit.
Each exchange caters to a different demographic and Language ,
For example : Cryptopia is more favorable to English Speakers,
Where as Yobit is more favorable to Native Russian & Chinese Speakers.
Basically you are selling a product (HBN) , sticking with only 1 exchange
(Even Thru Cryptopia is a Great Exchange) ,
is like only selling your product on only 1 side of a street and ignoring the other side.
You sell on Both Sides and Double your Customer Base.

IMO, go with the .1 BTC not the .5 BTC and just make sure to post the exchange update to coinmarketcap and update the OP.
Plus you always want more than 1 exchange, for the times when the wallets need maintenance.

I wonder how many new people could get interested in HBN by introducing a new exchange. I'd say not many unless you have a trade volume high enough to end up somewhere in the top ten of the traded pairs on that exchange.
That's why I don't think It will help much. Better keep all trading focused. (And make it to the second best traded pair today on Cryptopia)