How come the startpost is gone?

But you never detailed exactly what you want...
Yes, 2.4GHz transmitters sounds better but we have played with the old 27/30/40/75mhz system for many decades and for sure now with all people over to 2.4ghz you should have less issues with them. Yes newer transmitters have fast response technology but it does need digital servo's. If you have analog servo's you can not use any fast response so you will not gain an advantage. And the need is only real usefull when racing is involved.

Changing brushed to brushless is mostly done to go faster alhough there is a wide range of motors to find. To gove the right advise is determined of what the goal is.