Well I'm thinking of going the Tunze route myself for a few reasons
1. I'm tired of the "controller fee" added to the cost of each vortech, literally $75 added on to each, where as Tunze has you buy a separate controller if you so desire that level of control or go with a 3rd party, or hell even DIY since it's simply a small voltage swing that's doing it. It really upset me when the no longer sold the older Vortechs (again $75 cheaper)
2. Flow wise the 6105 is basically the same as the MP40, at around $90 cheaper. Plus the built in magnet of the Stream2 series removes yet another expense that was previously added to the Tunze Streams
3. My tank is 3 feet front to back, with the pumps on the back wall, I don't think the "ugly pump in the tank syndrome" is really an issue in that setup, sure there is a wire, but I think I can live with a wire in the tank.
Don't get me wrong, I love my 3 vortechs, and the service has been top notch, there have been a multitude of issues, like every few months they get a bit too gunked up with calcification or something and literally rip themselves off the walls, but I expect this sort of thing with all pumps as it becomes my ritual maintenance. I have a separate shaft/ceramic disk that I simply swap out while the other soaks in vinegar. I do plan on keeping my vortechs too, sorry no cheap deals to be had

I would get more vortechs but again, that price difference all because EcoTech decided that a wireless controller needed to be added to each pump really hurts, sure if I find them for cheap used or something I'll go that route, or if one of the LFS has a *wink wink* discount on them (The MAP really on these things pisses me off too! Since it gives no incentive for others to have cheap... which I think was the whole point of the matter). Also with that and EcoTech recently releasing devkits for 3rd party controllers it really makes me wonder about the controller, I can only hope they make one without the controller on board and simply a wireless connector to go with whatever 3rd party controller comes out so you can get a cheaper pump out there.
But if I had to throw 4 of these in a tank at once, I might just go with a couple of 6205s instead, or hell maybe a couple 6305s. So my next tank I'll need to think long and hard about what I'll be doing for flow.