IThe only down side is that it's a 45 minute drive 1 way. I make it to 2 classes/week. I live in a part of the world where there's not a ton of choices when it comes to dojos.
Well, it is what it is. If a 45 minute commute is challenging to you, there's nothing more to be said about it. However...I don't think I have ever lived anywhere where I had less
than a 45 minute commute to the dojo. When I was in Boston, it was 45 minutes (or more) walking and by subway to the karate dojo, or about the same to drive to where we would train shindo muso ryu jodo. Now that I live out in the hills, it's about a 45 minute drive to the dojo down in the valley. My commute is typical for our dojo members, who are quite spread out.
This isn't really the "20 miles, through the snow, uphill, both ways" lecture that it may sound like. I'm not saying "suck it up and do the 45 minute commute". I'm just pointing out that studying martial arts is time-consuming. I left home tonight at a little after 5 to get to the dojo, I stopped on the way home to do an errand that took about 15 minutes, and I got home at about 9:30. That is a big chunk of time. Most people simply can't make that kind of time in their lives. More to the point here, I think if you look closely at the Tomiki school, you'll find that the difference in the commute (of what, 20 minutes?) doesn't make much difference in the time that training will take out of your life. If time is a big consideration, I'd really suggest looking carefully at what time will be involved, including commute, time to change, training, changing again, dojo chores, back home. The question may not come down to Birankai vs. Tomiki, but aikido vs. no aikido.
Also, I wasn't a fly on the wall when you visited the Tomiki school, but rapid advancement is a bit of a yellow light for me, particularly if it was they and not you who called attention to it. Forget whether the typical time to black belt is only a year and a half, and ask yourself this: in a year and a half's study at the Tomiki dojo, do you think you would be as proficient as a black belt from the Birankai dojo? Did you see something at the Tomiki dojo that led you to believe that they had some way of helping you to not just advance in rank more rapidly, but develop proficiency in aikido more quickly?
Best of luck with it,