wow nobody likes the greats any more?
Your average CarAudio.com forum member (ages 16 to 18) hasn't very likely heard (of) either -- hence, that's why you're going to get a pretty limited response.
You might wanna check out
http://www.elitecaraudio.com or
http://www.diymobileaudio.com forums as the folks on both fit in a different demographic are have more experience with both drivers.
I'm assuming you're looking for a dedicated midbass in a 3-way frontstage? Or simply a mid/bass in a 2-way setup? Hence, the comparison between the Profi W165 kick and the Seas Lotus Reference RW165.
I'm gonna let you know that I have not heard either [yet], but based on what I know/have read, I'd go with the Seas but wouldn't hesitate to use the Rainbow. To me, the Seas Lotus woofer seems like the proven performer and I haven't heard a single bad thing anybody has to say about it. The Lotus is notorious for offering some of the best midbass from ANY speaker with great off-axis response.
Haven't heard/read too much about the Profi, but it
IS Rainbow and you really can't go wrong with that.
I believe 3.5max6spd has/had some Profi's (I could be mistaken). You should PM him and ask what he thinks.