Nick Adams, lead engineer on the Croft project (Elise) purchased a 23 a year or so ago and is currently restoring it with plans to race it.
As for comparisons...
1) You can feel the weight of the Elise. A 23 to an Elise is like an Elise to a Vette.
2) You can imagine faster response? 23 is much quicker than the Elise.
3) 23 = harsher ride. No rubber in the suspension, all rod ends
4) 23 = lots of vibrations. The Twin Cam has a inherent vibration around 6500 rpm and the engine/transaxle are solid mounted to the chassis. All of that goes straight into your backside
5) In a 23 your head gets banged around by wind buffeting.
6) In a 23 your ears are only 12" from the Twink, ear plugs are required.
7) 23 understeers in low speed corners, but is neutral in mid to high speed corners. Like the Elise it likes straightline braking, throttle on thru the corner. You don't want to lift mid-corner in a 23.
8) 23 shift mechanism is pretty heavy, there's a long hollow tube rod with a couple U-joints from the shift lever to the back of the Hewland. Also, the Hewland is fitted with straight cut gears, so there's lots of gear whine and double clutch downshifts are neccessary. Up shifts can be done with a slight throttle lift and a tug on the shift lever (no clutch).
9) Sitting in the 23 and looking at an Elise will be like sitting in an Elise and looking at a SUV.
10) Power to weight? 23 = half the weight of the Elise with equal HP (Twink).
I too would like to own a 23 some day, but I've got my 41 to play with for now (a Lotus 41 is akin to a open wheel formula version of the 23).
Kiyoshi