This is exciting....
My son is almost 11 mos and still small for the MA (even on the lowest height setting) as he was premature. We were going to buy him a new carseat for his 1st Birthday in May ... A Big Boy Seat... (Plus mommy will be returning to work and we'll have a little extra income)But right now he'd fit better into a RA. I think I might wait to check out the newest seats unless he outgrows (height-wise) his bucket seat before they arrive in Canada. I'm looking for a gently used Britax seat, but they are almost impossible to find. (Just until we can afford a brand new one.)
How much does your ds weigh right now? The bottom slots on the MA are the same as the RA, so there isn't likely to be any difference in how he fits. There's such a small difference in price, that I'd recommend going with the MA even though your ds is small, just because you'll be able to get much more use out of it height wise even if you don't need the extra weight.
I'm not sure from your post if by big boy seat you just mean a convertible seat that you can use rf'ing , or if you're referring to the Frontier, so I just wanted to give you some info that you may not have come across before...
1yr AND 20lbs is the minimum for turning a child ff'ing. It is however, not what is safeST, and not what is recommended even by Transport Canada. Transport Canada says this in their 1-2-3-4 Car Time brochure:
Don’t be in a hurry to start using a forward-facing child seat. The longer you use a rear-facing infant-only seat, infant /child seat, or infant/child/booster seat that fits correctly, even past your baby’s first birthday, the safer your baby will be in a crash. Be sure to follow the manufacturer’s instructions for use and check the label for the weight and height that are allowed.
Here's a link to a youtube video that talks about the importance of rf'ing and why it's safer:
http://www.youtube.com/watch?v=psmUWg7QrC8
For a rear facing seat the straps need to be at or below his shoulders, if he's still tiny enough that the lowest slots on the MA are above his shoulders, then he's definitely too small to be ff'ing any time soon.
Please feel free to start a new thread asking any questions you may have and we'll be happy to answer them. There's a tech on this board who is from the Calgary area and may be able to help you if you need assistance. Her user name is Aidensmom02 if you'd like to PM her. :thumbsup: