I use a Sous Vide heater with a small 6.5 gallon tub from amazon that I use to bring everything to temp and I use that heated water for the rinse cycles, and replace water back into the tank as I use it. The Sous Vide heater heats the new replacement water to temp very quickly.
The Ago compensates for temperature drops as it develops film, which I find to be very convenient. It has an audible beep at 10 seconds to end time of whatever development stage you are at, so you can do something else while it develops and have an audible warning to return back for the next step. Plus, it has the convenience of custom programs for different B&W chemistry development times and I don't have to sit at the machine with a timer or my phone the whole time.
I do make sure with C-41, E-6, and B&W that every step starts with the same temperature chemicals and water. I have used C-41, Kodak and Adox chemicals and for E-6, Adox and Film Photography Project (Unicolor). I haven't had any problems with them. The Film Photography Project (Unicolor) Chemicals do have instructions for development at 70°F but the 1st developer stage is 26 minutes vs 6.5 minutes for 105°F. I have never tried it at 70°F though I may try it now and see what happens.
If you have more questions feel free to ask.
Jess