I've used most of the available soldering irons, and have kept the 898D+ 2 in 1, because it is easy to set the temp, and easy to swap tips. and the tips seem to last a lot longer than others. Doesn't make noise either in my ear, or in the radios. HOWEVER, the care and maintenance of the tip is essential on all of these irons.
And I echo the warnings to stay away from acid core.. that is a no brainer.. and to stay clear away from no lead solder.. that is a certainty for return repairs, especially on board kits that are intended to be portable
or moved much at all, SMD OR hole thru! No amount of temp control, flow control, elasticity of the solder, or not, will "fix" the issues with no lead. No lead is simply a marketing tool, that has NO application to longevity of use, or reliability of connections.
Good Luck with the builds.
Let me add, one tiny note.. the setting of temp, and the amount of time actually on the connection, combine to make up reliable connection.. or not. Too much, of either is a real bad thing. Not enough heat and too long..
is still very poor, too much heat, very little time.. just enough to flow is ok.. and setting the temp then controlling the time on is the easiest and most repeatable.
Have a great day,
--... ...-- Dale - WC7S in Wy
"Actions speak louder than words"
1856 - Abraham Lincoln