I've been usin the "Comfort" brand car seat in my E (bought it the same day, 'cause the old one didn't match). The LATCH system is sweet! I've been using the old seatbelt style carseats for about 4 years now, and the safety in this new system is obvious. Also, WAY easier to get it in secure. The thing I like about the Element and carseats is the ease of loading and unloading my daughter. She loves it because she has the best view in the house (including the sunroof). I found that the upper strap is easier to "snug" up if you recline the seat you're mounting it to just one notch, tighten it (afore mentioned strap), then raise the seat back up to fully upright. Also, I bought a (color matched, of course) floor mat, folded in half (soft side out), and placed this under the carseat to avoid leaving any unsightly grooves in the Element's seat. I folded it in half because it is twice as big as it needs to be, the abrasive side is not in contact with anything but itself, and it makes the barrier twice as thick. You can't get away with putting anything under a car seat if you're using the seatbelt style system, but with the LATCH type, the secure-ness (?) of the carseat is not dependant on upper body strength, and is not held "down" onto the seat (ie, it cannot work loose, if the floormat, towel, blanket, etc., under the car seat works loose).
-Anthony
PS. Honda rules!