Well, if I were you I would just get a single session of HB and continue to use Sgather as it is an excellent bot. If flying is important to you as well as having a paid-for gathering bot then get lifetime, but the price is pretty high in that case. What you will get with HB is a very good grind bot, an instance bot that does pretty well, an archeology bot that will use a ground mount, a pvp bot that will join BG's for you and farm them for honor, as well as a quest bot that will give you alot of trouble and not be much use at this time. Oh ya you can also use ground mount herb/mineral farming that works really well.
I notice you say you will be pvping alot after gettting to 85, im not sure if you mean you will be wanting to use the bot for some of that or not but, pvp with HB is best used for farming honor in BG's.. thats it. Most cc's are not written with pure pvp in mind as well as it being hard to guess a human players next move as compared to a pve mob. As a result if your bot ever gets into a head to head duel with a human, the bot will have his ass handed to him generally speaking that is. But for what it does, it does it pretty well(farms honor).