I'll just add to all the pro-Britax / pro-rear facing posts.
Please, please, please do the research. Read up on the safety issues. We, as adults, put our own thoughts and feelings upon our children with regards to "riding in cars" -- meaning, WE think they are uncomfortable with either facing to the rear, bent legs, or not being able to "see the world." But, watch your children when they are playing. Often, a child's preferred way of sitting will be with bent legs. Unlike adults, children are not uncomfortable. Additionally, unless they are already forward facing, it's not as if they "know" that they are "missing" anything. My DS stayed rear-facing until he was 2.5 years old and 31 lbs. Personally, I wish I had left him until now as he has just now reached the upper weight limit (33 lbs.) at 3.5 years old.
I'm not sure why so many people are in such a rush to turn their children around. Safety should be, first and foremost in our minds with regards to our children. Convenience or avoiding paying for a car seat should not.
Yes, Britax is rated highly. Yes, we have a Britax. However, I did not pay anywhere near retail as there are several internet sites which sell them at a discounted rate. There are several online boards where you can ask car seat techs their advice. There are other convertible car seats which are not as cost prohibitive and are ranked fairly high with regards to safety.
I have no doubt that you love your sons and want to do what is best for them. I do urge you to look at all the pros and cons, including watching some of the videos on the reasons for extended rear-facing. Many parents I know haven't watched them simply because they KNOW that it will make them feel guilty for even thinking about turning their child around to soon.
Ultimately, it is your decision as a parent. A previous poster mentioned the Graco Nautilus. If you are planning to turn them around at the legally-accepted minimum of 1 year AND 20 lbs., this would be a good car seat to own.
On a side note, the post from Sindy, "...PS my girls were 20lbs and front facing at 4 and 5 months" not only advocates irresponsible parenting, it supports illegal behavior. I highly recommend ignoring that post.
Best of luck. Car seats are a financial burden, but in the end it's better to be safe, you know?