A front splitter on a road car is more about eliminating lift, rather than creating any significant downforce. So it should help with handling at speed, but mainly just by maintaining the balance that you'd have at slower speeds.
I think the late model 'wheel flaps' are available to buy through some sites, and are meant to make a reasonable difference. The front end float at speed isn't just limited to MR2s, any car with poor aerodynamics will experience it. But the rear weight bias would certainly make it more noticeable.

I understand that there is nothing that can be done about the weight balance of these cars but wont eliminating lift at high speeds help with front end stability and feel?

I wouldn't say weight dist can't be done, you can always keep spare wheel and get lightweight exhaust to make it more front heavy by a little. However rear bias weight  is still advantageous in braking and grip under acceleration

Disgree with you there, weight in rear means less weight on front, so less effective braking.
The front does most of the braking.
Add some stiffer springs and braking will be even worse due to less weight shift to the front.
It definitely improves traction under acceleration though.

Dont tempt fate by driving the sw20 in the wet in a silly manner, specially in corners when its wet, lots of Sw20s have been written off or damaged that way
just be safe. good tyres are very important and so is a staggered width set of rims with the rear being wider.
going in slowly in the corners and powering out seems to be the way to do it.
and yeah never lift off  while taking corners, i have doen it before and got lucky cause i wasnt going fast.
 
The SW20 will make you learn to drive properly.
cheers

Depends on what model you have. I drive MR2 turbo's differently to NA ones. Assuming alignment/tyres/brakes etc are adequate/operating correctly.
 
Turbo SW20 - hard braking @ corner entry, light throttle mid corner (don't let off) & boot it hard on clear exit (note a late trigger time compared to 4WD cars). Important not to get on the throttle too early with turbos
NA - Very much similar to the above, but a lot more aggressive, especially with corner exit
AW11 SC - Much like an NA SW20 but having more fun.....lol
 
In the rain I treat all MR2's like I'm driving on ice. Nothing aggressive, very gentle inputs. As I mentioned to Rob once, punching an MR2 turbo (ie downshifting/booting) in the rain is VERY dangerous, especially the higher powered ones. I did so in anger (someone kept cutting me off) & due to the typical uneven road surface, my car immediately turned 45degrees. Will keep my cool next time.
 
I highly recommend finding the limit of your MR2 safely. I did a few driver days (safety course when young too). Don't recommend it, but back in the day I found a massive open space out in the sticks & provoked my car to spin in the rain. Gave me a great idea of what I can & can't get away with.

Ideal driving style is not to crash:)

Actually I thought since there is less weight at the front it is less likely to lock up (unlike FF) so it is more "balanced" weight distribution under braking therefore you can brake harder. I know for a fact my NA SW20 brakes harder then my mates Skyline (R32 GTSt). 100-0 Km/h still quite good compared to cars these days, all things being equal

Vehicle dynamics is EXTREMELY complex, but generally speaking a rear weight bias is preferred for outright performance. That said, I believe the MR2 is a little too much rear biased.
A set of tyres give the most grip when the overall load is equally spread between them. So under braking when the load shifts to the front you lose outright grip. If you have a rear weight bias to begin with, you'll have a more even spread and better grip from the tyres. This is only realised if you have the correct brake bias. If your fronts lock well before the rears, you're not making the most of your tyres.
Acceleration for a RWD is obviously going to be better with more weight on the wheels.
 
Handling is much more about your spring rates, geometry, ARBs than weight bias. However having the centre of gravity towards the rear means the distance from your front tyres (where the steering happens) to the CG is longer. This acts like a lever, so your steering inputs are magnified. Combined with having a lower moment of inertia (all the weight towards the centre) is what gives the quick turn in response.

I could be wrong :)
I can see it could be more important to have the ideal brake bias to maximise effort across all four tyres, rather than weight distribution.