I don't think I would tie myself to any rebreather simply because the logistics of training sucks. That could wind up being a waste of 10k. I don't know much about the orca spirit. I haven't dove one. I do teach on the Sidewinder. And it's a great unit for what it was intended for. But, if the Orca is a BM version of that unit, NO WAY would I own one, for any reason or any accomodation. If you're really picking an inferior unit (and I don't know either way) because it's more convenient, then you're making a MONSTER mistake. And hopefully you're big enough to admit to yourself (and maybe others) that you screwed up to the tune of $10k. Most people can't admit that they made a bad purchase when that kind of money is involved. There are a dozen threads here about how I feel about the rEvo for exactly that reason. I bought one because it was practically given to me and the class was free. If I had a time machine, two things would happen for sure. I would have realized that hot red head was trying to bone me in 10th grade, and I would have never bought a revo.
With all that said, we know you well enough to know that you are going to do what you wanted to do before you even posted this thread. But, most of us are bored and so we entertain. You'll buy the Orca, you'll likely hate it, but because of something as simple as finding an instructor that offers great units, never change.
On the other hand, I have dove every single version of the Optima, and the BM or OTSCL or CM Optima are both fantastic units. I wouldn't hesitate to buy new or used on either units. I believe the OTSCL unit is one of the best breathing CCR on the market, and I've dove nearly all the current units. Parts are cheap, Dive Rite has fantastic customer support, and Lamar is patient even with the likes of me. AND, your instructor teaches on that unit.
You like to cave dive, or at least when I frequented the board, you seemed to. Go to cave country (in any country), when Optima's out number Orca's 20 to 1 anywhere cave divers are present, you have to know there is a reason.