This is my review:
I have Tunze 6100's, Tunze 6025 and 6045's as well as different size Korallias and this SF1600 on MJ1200.
The Sure Flow's flow pattern is waaaaaaaay better than the Korallia's sideways "V" flow pattern. The SF's is more like a wall of water similar to the bigger Tunze's.
The SureGrip magnet holder is a must with the Sure FLow 1600 mod but it is FAR better than the Korallia and both Tunze's magnet holders. This magnet is what adds to the cost of the total unit because yu have to buy it separately.
The holders on the smaller Tunzes are a complete joke and waste of time. I;m talking about the ones on the 6025 and 6045's. The little tabs break off very easily and the Tunze pump unit DOES NOT stay clipped on to the inside magnet very well. (But i have to admit that we are constantly manhandling all our powerheads in efforts to aim them better at our livestock.)
The large Tunze magent holders hold well BUT the Sure Grip holds just as well AND is more compact. It is less wide so therefore you can squeeze it into tight spots better.
All in all im pretty impressed with the Sure Flow 1600 however you need to add the cost of the actual powerhead unit and the Sure Grip magnet holder.
Personally i like the look of the SF1600 better than the Korallia's but that;s a very personal choice, i think.
I would definately buy this product again and probably before any Korallias evethough i've been pretty happy with the Korallias just not as happy as with the SureFlow/SureGrip/MaxiJet combo.
Hope this helps anyone who is trying to decide,
JOHNNY