I am splitting my season between my ITR Teg R and my Del Sol. On 225 55 14 hoosiers, it handles like a CRX. You can just throw it into a turn and the backend sticks, and you floor it and goes. On both the teg r I own and a 95 ITA teg I rented, they just don't want to hang the back end out like the sol. Soooo if you like getting a car sideways and stomping people into turns, the sol is an interesting choice.
But therin lies the rub. At 2250 (or whatever it weighs) the CRX 1.6 handles better and seems to not give up a lot of power to the SOHC 1.6 Sol at 2550. I suspect racing a CRX with a Sol you will give up a bit on every turn and not make it up on the straight.
Meanwhile, if you want to run a 2550 pound Sol, the 1.8 tegs sem to be making good power. I suspect if you run the Sol against a teg, you wil find you can go into a turn harder and deeper, but at the end of a long straight I think you will have a teg beside or ahead of you.
So, why run a Sol? well if you like the road less traveled the sol is the car for you. It handles like a CRX though the front tires do a lot more work carrying the extra weight than a CRX does . It is also a lot more stout than a CRX in front supension hubs, uprights, and structure. I wouldn't worry about the cage, Punch the rear brace though the rear panel below the window, I can send pictures. At least mine is plenty stiff.
Anyway, my 2 cents is that there is no clear best for ITA. For the money a fully developed used CRX is a great car. However you need to maintain hubs carefully and you need to inspect carefully for cracking in rear and front suspension mounts. I would be wary if you we looking at a CRX with a lot of races (60 or more) as CRX tubs definitely wear out. And when that happens, they tend to break corners off.
If you are building from scratch the Sol or the teg are great options, but these require $$$$ in engine as suspension development.