Newborns fit well in both the True Fit and the My Ride (sometimes better in the My Ride than in the Graco buckets!) It would not be unsafe to use the convertible right from birth. You could use the $100-150 you saved on an infant bucket towards a really nice baby sling or wrap, instead of carrying baby in the car seat.
If you are set on the infant seat... There is no way to know if one car seat is safer than another. The only info we have access to is whether or not they passed the safety tests. All seats on the market passed the safety test (obviously). So, if the car seat installs well in your car and fits your baby well, it is as safe of a car seat as you can buy.
I skipped the travel system. I didn't ever like any of the strollers that came with the systems. They were too huge and heavy. I figured, I'd rather invest in the perfect stroller, since I'd be using that years after getting rid of the infant seat. Several non travel system strollers can accommodate infant seats (some require an additional adapter). Or, you could get a Snap-N-Go type thing that fits almost any infant seat, which would buy you some time to find the perfect long-term stroller, like a Maclaren or BOB.
Personally, I find it to be a giant pain to have an infant seat that requires that the handle be down in the car (been there, done that). For that reason alone, I'd skip the Baby Trend seat.
You are right, the main benefit to the higher limit seats is that they fit babies longer. If you're not planning to use the infant seat more than a few months, this might not be a selling point for you. However, the regular Snugride (the 22 pound version), has very high bottom harness slots, and does not always fit small newborns well (the harness slot must be at or below the level of the baby's shoulders). I'd skip that one too. The Snugride 32 and 35 actually fit small babies better!
The Safety First On Board could be a good choice. It is not too pricey, it has low bottom harness slots, so that it fits even tiny newborns. It fits tall, heavy babies too, in case you did want to use it for a long time (or, have it on hand as a back-up or travel seat). My skinny boy still fit height-wise and weight-wise at 2 years old!
The Chicco infant seats are also great. They're well padded, easy to install, fit small newborns well, etc.
The best way to shop would be to head to a store like Babies R Us, where you can take the seats out to your car to see how well they fit/install. Then, choose a seat that has low bottom harness slots, and preferably a front harness adjuster strap. This mechanism makes it much easier to get the straps tightened well, vs. the clumsy adjust-in-back style common in less expensive seats.
Good luck and congratulations on your new little one!
