Hi KimVan
We started before OTA's became popular and never have used them so I can't tell about what difference they might make in booking, however please keep the important numbers in mind. In my mind anyway it is not the total number of bookings or revenue that is important, the important number is how much we have after doing the work and paying the bills.
Think long and hard about it, after commissions, after the extra work, yours or labor you are paying, after extra wear and tear, maintenance to your property, because you have extra guests, have you really improved your bottom line enough to offset the extra work and stress? I can only speak for me, but for me, I'm happy, I don't think the extra stress and work would be worth using them.
Think also about how you could promote yourself if needed with that percentage you would be paying the OTA, bet a fellow could purchase quite a bit of advertising and not have to sell your soul to the OTA, just my view. Feel free to send me a PM, I don't object to sharing.
If you (your business) has had a website for a while I would think you would be getting exposure, if guests only find you as a result of an OTA search and they book through the OTA, well I don't think that's doing you any favors. Consider using a pay per click model with TA or someone to promote yourself and get your information available to guests.