I have 3 SL35-E/VSL35-E bodies which work (well, one's BC and self timer doesn't), this after going through at least 2 bodies which had the "lazy mirror" problem. So a better than even success rate isn't too bad...
The original SL2000 used the same shutter (and apparently electronics) as the SL35-E, thus was prone to the same failures.
Later and fixed SL2000s are the so-called "3003 inside" model which, (you guessed it) have the upgraded and more reliable electronics of the 3003. Their shutter also reaches 1/2000 in automatic mode (on the SL35-E and normal SL2000s the shutter was originally designed to reach 1/2000 but was slowed to 1/1000 maximum because of reliability problems).
The 3001 is basically a simplified 3003 without the WLF.
On all these, using batteries or accumulartors other than NiCds can damage the electronics in some situations.
Also, the later film magazines are said to be more reliable than the earlier ones having the manual film length setting (though these too were often upgraded "inside")...
So, definitely not for the fainthearted! But can be great fun.