I don't know what anyone else said / I didn't read above at all, but:
I have two bone stock B234F engined cars:
90 740 GLE AW72L 4.1 rear
88 240 GL AW72L 3.73 rear
They both could probably do with new plugs, but:
240 has FreeEMS, no airbox/airfilter so is noisy, pseudo wasted spark with toyota COPs and an untuned flat 75 or 80% VE table that's a bit lean around peak torque but I just run 98 RON fuel in it and it doesn't ping like that. Algorithms are good enough to daily like this.
Comparing the two:
240 is more responsive / strong down low and feels strong through mid range despite tall diff
740 can be hesitant when cold and at lower RPMs but sings well through to 6k hard cut
240 can rev a bit higher, but the valve springs are border line at 6000 anyway, so not much and you have to hold the box from shifting to achieve it
240 starts immediately with my code, but YMMV on megasquirt...
740 starts fine, but not as quickly because OEM was primitive/crap
240 has no idle valve or control so must be warmed up manually with the gas pedal and/or while driving
740 idles a little low cold, initially, but settles fairly quickly, idle valve probably dirty/sticky/etc
240 is running some crusty old firmware from ages ago without:
1) any accel enrichment - so lean pops audible if you stab it suddenly at the wrong time but hesitation minimal due to base algorithms and design
2) new precision smooth RPM code I intricately designed and developed but never widely rolled out - in practice this doesn't matter much, but knowing it's accurate to 0.5 RPM to 4000 RPM and < 1RPM to redline is nice compared to eg MS1 that is at best accurate to 100RPM
various other enhancements that I can't recall right now. Basically I'm dog fooding and I've been dailying the car with no wideband and no tune for a little over 2 years now without major complaints (gas mileage is okay, 350km/tank vs 400/tank in the OEM car). No fouled plugs or any other issues. Had it to about 100mph when I didn't have a 4th gear with OD wire cut. Probably haven't had the 740 higher but have taken the 740 to a drag event and drift event. YT clip of B234F donuts on tail of drag strip at drift day here:
https://www.youtube.com/watch?v=Ds3wSdXyf9Q
My plans are to develop an NA tune in the car for my lighter 360 hatchback including cams and ITBs and then swap that gear into the smaller car and develop a mild turbo setup for my 240 wagon in this, then swap that out and not sure after that, maybe the BMW V12 I intended to put in it. A standalone gives you options to expand, but the differences are NOT worth it unless you're swapping chassis like I was. No room for that dizzy, no factory EFI loom or pump etc, custom loom by me.
To get OEM like driveability and economy and power will take you quite a bit of work and any gains will be minimal, eg less than 10% or so. IE, not worth it unless you have plans like I do to make more power and or aspirate differently. If you had a manual being able to get valve springs into it and raise the rev limit with some mild cams would be totally worth it.
My 2c.