Here is a link to the "tools n tips" forum at ARC (Aircraft Resource Center), you can browse without being a member;
http://www.arcforums.com/forums/air/index.php?showforum=12
I have an H&S Infinity 2 in 1, with most of the extras & have to say I am delighted with it. I have heard many people harp on about the unjustified prices of H&S brushes, but I don't agree that the debate is worthy. Yes the H&S stuff is expensive, but it is a top quality range of product in my humble opinion.
Their brushes are exquisitely built & finished, they are easily cleaned & produce good results. The vast majority of the brush can be stripped down without any tools, the rear of the brush doesn't even have to come of to remove the needle. Spares are also very well priced, unlike some other "premium" brands.
I would advise that the 2.0 & 4.0mm needle / nozzle sets are the most useful, the 2.0mm being a decent jack of all trades & the 4.0mm being good for larger coverage. Be aware that the Infinity Solo kit only comes with a 1.5mm needle / nozzle set, & while this is great for very fine detail, it is not so suited for larger work.
As has been said many times here, your best bet is probably an internal mix, dual action, gravity fed brush (also keep in mind that H&S provide siphon bottle conversion fittings for their gravity brushes - again at a reasonable price).
If you fancy an H&S product & can afford it, I wouldn't hesitate - just remember to leave some money spare for a decent compressor!