Nothing wrong with either jet, fan or needle.
Peter Fogwill uses (or used) fan jets in his brushes, he adapted the brushes accordingly by removing a couple of rows of bristles on the inside of the brush, this allows the 'fan' of water an even, uninterrupted flow of water onto the glass, the outer bristles of the brush trap the 'fan' thereby preventing overspray.
The jets are smaller in diameter so that for a given pressure you get a good spray pattern and should also be able to use less later. This though depends on the water pressure you decide to use.
Are fan jets as effective as needle jets?
Of course they are! People talk all the time of rinsing off the glass, well I for one almost never have done (dependant on the situation) regardless of whether I was using fan jets or needle jets, if anything, for rinsing off the glass the fan jet is better - a greater force of water over the entire width of the brush, meaning you can direct a wide rinse from top to bottom of the window.
You need a good fan jet and a properly adapted brush though.
Oh, in case anyone is wondering, I use needle jets...but only because the brushes that Peter supplies (or did supply) were too heavy, the Gardiner brushes are suburb brushes, light and very effective, but if Alex ever supplied an adapted brush and fan jets I would use them for sure...oh, Peter Fogwill I believe mills his own jets.
Ian