There are certain people that I coach who I am actually considering giving me vasa ergometer to to make them finally get the idea of a catch and show them how little useful power they generate. I, on the other hand, use it rarely. Much like any other piece of indoor equipment, if you use it it will work.
Interestingly, this type of thing is probably one of the few out of the water things to be shown to improve swim speed in trained swimmers, although that is second hand info as the study was published in a polish journal.
I don’t know these guys who are saying it is very hard to use so it’s hard to say, my impression is that if that is the case then you may be using the wrong muscles or possibly you are just not very strong, just don’t put out the requisite power to go fast - I’d be interested to know their typical tri splits.
Having the door open on the 2 setting is easier force-wise than normal swimming is for me and having it on the 3 setting is a little harder.
One thing about it is that when going back to the pool I need about 500 - 600 yards to get my groove back. At first I feel very powerful but I am putting that power out without a lot of payback. After 500 or so everything feels back to normal, this seems natural since the movements are a bit different.
People say that it helps pull technique, I’d say it CAN help. One thing you do get is that you are always exerting force through the wire, this means you are always pulling or pushing more or less backward. In my opinion many many people use a lot of effort pushing down, to the side or even forward, so you do have this going for you. The cord is attached out in front of you, even when your hand is not exactly pulling straight back, it is “mostly” backward.
On the other hand, you can look online and see a video of a guy showing off his vasa trainer ability and he is obviously doing it with dropped elbows (he’s a musclehead so it doesn’t matter to him). But you can definitely do it on the ergometer as well, pull lots of watts but have your hands in totally the wrong position. If you got the halo board with it I think it would pretty much eliminate that possibility. But be aware that while you CAN use it to reinforce good technique, you can just as easily use it to reinforce dropped elbow pulling.
I’d put it this way, if you can’t get to a pool, then the vasa will help you if you use it. I mean what else are you going to do? If you are the type of person who is only at the pool maybe once per week this would probably still hold.
Also if your catch and pull just really suck big time then it can also be helpful for you. So if you fit into either of those two categories I’d recommend it assuming you will use the thing.
If on the other hand you are the type of guy who hits the pool three times per week pretty steadily then the value proposition is not as clear.