As with any electronic studio flash, the flash tube and modelling lamp are consumable commodities, and are designed for easy user replacement. I've used Bowens flash units professionally and I've never known one of their flash tubes to wear out, but their exposed position on the front of the head means that they are a bit prone to accidental damage if you're careless. Modelling lamp bulbs on the other hand burn out with monotonous regularly, and they are fairly expensive. The recommended Halostar 250W bulbs cost around £17 each, and only last for about 150 hours. The Gemini 400 incorporates a bulb-saving feature that turns the modelling lamp off after 30 minutes if the flash hasn't been adjusted or fired, but nonetheless one of the modelling lamps burned out while I was testing the kit. The flash will still work of course, but without the modelling lamp it's hard to judge what the shot will look like. I have previously used 200W screw-fit domestic lightbulbs as replacement modelling lights, but in today's energy-conscious times these are getting difficult to find.
In actual use the Gemini 400/400 kit is very good. The easy controllability, reliably consistent power output and colour temperature, and fast recharge time meant an afternoon modelling shoot went without a hitch (apart from the quickly replaced blown modelling lamp bulb) and produced some excellent results. The only problem I encountered was that one of the slave cells seemed to be a bit too sensitive and kept triggering the flash whenever the modelling lamp on the other unit was turned up, but that was caused at least in part by shooting in a very small room with the lights close together. Simply switching which light was synced to the camera solved the issue.
The 400/400 kit may be and expensive accessory for the amateur photographer, but it is actually pretty good value for money. The Gemini 400 heads are priced at around £260 each, so you're effectively getting the stands, brollies and bag for free. It would be nice if it was available with a soft-box and a brolly as an alternative to two brollies, but that's a minor quibble, and if you buy from a high street shop you might be able to persuade them to do this for you anyway. As it stands the Gemini 400/400 kit would make an ideal starter kit for any hobby studio, or even as a portable alternative rig for a working professional.
The Bowens Gemini 400/400 twin-head starter flash kit is made to the same high standard as Bowens' professional equipment. It offers robust build quality, simple easy-to-use design and reliably consistent results. It can be the foundation of a growing studio system, while its portability and the versatility of optional battery power make it a good choice for outdoor location shooting.