Hi,
I own a KayakFirst erg and love it. I also have the sliding seat option, and added a rotating seat.
My thoughts/opinions:
-Compactness - Takes up very little space compared to traditional kayak ergs, including the height requirements. Since the shaft is much shorter, not as much over head is needed...which was a big deal in my low ceiling basement.
-Sound - Much quieter, and a different type sound then my previous traditional erg, as well as our Concept rowing Erg. Feedback from my family upstairs is not sure I was doing an erg when in past knew they knew if I was on kayak erg, or rowing erg.
-Max Resistance - I found on my previous erg I had to always have the drag maxed to make realistic. On the KayakFirst this is not a problem. Matter of fact, I have not used on the max drag setting for my current workouts. Nice to have more drag available as I progress into my winter routine. Will allow to do some more strength/lower cadence workouts.
-Realistic Catch - With the adjustable pulleys higher, you get a much more realistic catch IMHO. When "spearing" at the catch, the motions seems very realistic - driving down vs more just pulling back like my traditional erg. This was probably my biggest positive surprise when I started using
-High Cadence - My fastest cadence is 125 spm and this erg has no issues keeping up and since shorter lines not as much excess line flying around. Sprint cadence seems very realistic like my marathon cadence (85-88).
-Sliding Seat - This has also been a pleasant surprise. A pricey option, but really does add to the realistic motion. If my rotation/leg drive motion is not timed right, the sliding mechanism will reflect this...giving way too much back and forth motion, ie wasted energy. When I focus on my timing to get aligned, instant feedback with the sliding mechanism...like my K1.
-Mirror - Nice touch. Not wide enough to see stroke exit, but definitely helping me with timing and top hand placement...great to work on muscle memory in off season
-Quality - Have had mine since April (didn't use much in summer) and no issues. Very well built, sturdy and seems like will last long time.
-Display/Monitor - Has been very reliable, nice to be able to create custom displays. Meaning which of the fields you want to display and in which order. Unfortunately does allow you to create your own default (have to set up each time). They are working on this. Also not HR connection.. Easy to solve, I just use my Garmin 520 on the pull bar.
-Mobile App - Great idea, but still a work in progress to some degree. I have raced against others which is a cool out of the box -no charge, but the setup and creation of workouts not where it needs to be yet. They are working on this from what I understand. I've been just using workings on my Garmin like I do on the water and works great. Have the proper fields on the KF monitor, and workout on the Garmin
-Company - I'm in the US, and have had some phone chats, emails, etc with KayakFirst about setup and mobile app. Great group and very responsive
Hope this helps, let me know if any additional questions
Chris