I have the Interfit EX150 Mk2 kit, and am really impressed. I did a mini-review on another forum, but have pasted it below.
So, last night (after dinner), I unpacked my Interfit EX150 Mk2 kit. Aside from the fact that one head is faulty (spoke to returns, and they're sending me a new kit, and they also said that they get no more faulty heads than with Elinchrom, so not to be scared off by the fact one head was faulty), here is my mini review.
Initial Impression
The box is well packed, but there is no leaflet or instruction manual (there's a DVD), so if you're a lighting newbie, you will need to watch the DVD to check how to assemble everything safely.
Features
The heads are 150w heads which is more than adequate for work in smaller spaces - 6 foot away with one head I was shooting at f/8 ISO 100, so no worries there!
The heads have a ready beep, which was beeping nice and quickly - only 1.5sec between exposures at around 3/4 power.
It's worth noting that the modelling light is proportional to flash output, and works quite nicely.
The heads have stepless output, so you can adjust the output to a fine degree of control.
It has an Elinchrom bayonet mount, so you can get Elinchrom accessories.
The kit comes with one umbrella, one softbox, but two reflectors, so if you want an umbrella on both, you just need to buy an extra umbrella. It also comes with air cushioned (at this price! wow!) stands too.
Oh, the kit also comes with a DVD which shows you how to put everything together, and a basic lighting setup. It doesn't show you how to get the exposure right, nor does it advocate use of a flash meter, which I find odd, but, for someone who has never used studio equipment before, it will get you up and running - and if you're reading this review, and thinking of buying it, you can ask me, or other people in the forum how to do that kind of stuff

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Ah, and one last thing, it also comes with 3 spare fuses, which is good

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Build Quality
Having gotten used to borrowing a studio fully equipped with top-end Elinchrom and Manfrotto lights and stands, I was a bit worried, but unnecessarily so. Sure the lights are not built like tanks, but to use a lens analogy, if the Elinchrom's are like Canon L lenses, then these were like the 85mm f/1.8 - well built, reassuringly solid, but just can't take the abuse that the Elinchrom's could (having said that, the bulbs are so delicate anyway, you should baby all flash equipment!).
The stands are not the best, but air-cushioned at this price is impressive. Manfrotto should take note - the only reason that the stands are not amazing is that the air-cushioning is not too smooth, but for the weight, the stands feel good.
The brolly? Absolutely fine.
The softbox was a bit awkward to put together - not complicated, just awkward getting the 'spokes' in that form the frame.
Results
The results were impressive. The light recycled quickly, and consistency from shot to shot was very good - meter with a light meter, and the variation between shots was only around 0.2 stops - easily correctible in RAW files - I don't know how much success you'd have with JPEGs - I've never tried to rescue clipped highlight detail from JPEGs.
Conclusion
Wow! This kit is amazing value. It's a shame it doesn't come with a bag, but is nit-picking. For the money, it's really, really good, and combine with a Sekonic L308s flash meter, and you've got a great home studio.
Update - so, my kit was replaced, and the new one is flawless

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The photo below displays the rear of the strobe head, and all the controls.
For those of you interested - here's how the business end looks.