A flash is a flash, IMHO. The best accessory is a coiled lead to allow for some modelling. If you must have on camera flash, I'd pick up a late model entry level Nikon for £25 which will have a pop up flash with rear curtain sync and all the under/over exposure settings and automation anyone could wish for.
But he's got a Leiaca MP and wants something to go on that.
The real question is whether he wants a flash unit with its own inbuilt auto function which reads the reflected light and and shuts off when its got enough light back or whether he's happy with manually setting output. If its the first then the sunpak is the cheapest and most versatile small unit available. If he wants manual output only then the Sunpak will do that too but the Fuji is much higher quality unit which will do it and is not very expensive.
And the other question is how he will be using it. If he hasn't got the time to work out which power output setting is required then a flash unit with inbuilt auto may be required. But with experience manual maybe OK as you'll soon know what power output to use in any situation.
Which you use is debateable becasue the auto units are dependant on the subject reflection which can often be wrong whereas manual, if you know what your're doing, will always be right or close to right but takes longer as you have to set it. Manual only may not be optimal for grab shots.
OP needs to make some choices based on what he thinks is best for how he wants to use it and his skill level.
p.s.
OP also need to check whether a small unit will obscure his view of camera controls.
