I'll tell you what I did. After having acquired many tanks for use in battling, keeping the parts common was important to me for 2 reasons. First it kept costs down. 2nd it made repairs quick because they all shared the same radios and electronics. Eventually I chose to upgrade 1 tank with El Mod but still run it through the HL board and radio. While most guys are running TK-RX14s and 18s all of my tanks are still powered by TK-RX13s and with plenty of spares.

Those tanks that are slated for installation with IR battle systems will get Darkith's, again to keep everything powered by HL.

A wrench has been thrown into the plans though. My next tanks will be the Mato Toys M4A1(76)W with completely different radios and electronics. So those tanks will have to be evaluated to see whether it pays to obtain spares to maintain their electronics or switch them over to HL components if they fail.

If you're still set on going the Tamiya route, consider this! Get one of Tamiya's static Tiger kits and put El Mod in them for the best of both. Of course that's mostly negated now with Asiatam's release of the metal Tiger I lower hull with working torsion bar suspension.

For economics, sticking with HL and Darkith's battle system is the way to go. It's got more features then Tamiya's Full Option system too.