Ahh yes. Fireball is stirring up crap is he?
In all fairness he has shot both rifles. He's shot my PE-90 target model and he has a SL8-4 that he did one heck of a job converting the thumb hole stock to something cool.
Here's the PE-90 target in the interest of keeping this thread going.
And here's Fireball's SL8 with home converted stock and AR15 magwell. It's a big improvement over the factory offering. Here's the thread he made on how to convert it. It's stickied on the top of the black and green rifles section.
This is what Fireball brings to the table when he's not thoroughly enjoying being a ####.
http://www.canadiangunnutz.com/forum/showthread.php?t=683332
Going to weigh in on my take of these two rifles.
The PE-90 is essentially an updated 1950s rifle. It's pretty much a highly modified and non crapy AK style design although not an AK and not a variant. They added some nice touches like the folding stock (usually hate these but this one is excellent), trigger guard that moves out of the way for gloves, side bolt release, adjustable gas block and wobbly built in bipod. The internals are like a Swiss watch. Exceptional. They are fairly accurate although can't keep up with an accurized AR rifle. The charging handle is still on the right hand side (Thanks Russians for bastardizing the STG44 when the Germans had it right back in 1942). Only the target model offers ease of adding optics. Although the regular ones come with some very nice drum aperture sights. Cost is over the top but they are exceptionally well built. Now comes in 1:7 twist rate but previously was 1:10.
The SL8 is essentially a 1990s rifle. The internals are mostly G36 which also shares components with the UMP. Mostly polymer, has a match type medium bull barrel and a crappy thumb hole stock that will either work for you or it won't. The ergonomic are better than the PE-90 when it doesn't have the thumb hole stock. Although I'm generally not a fan of the way the rail travels over the charging handle. But the charging handle does go either way and sits tucked in when not in use. Very reliable and accuracy seems to be good. Accuracy and triggers of both the SL8 and PE-90 are comparable. The SL8 costs a fortune to upgrade using any HK stuff. If you were to add the built in bipod and the G36 folding stock to make it comparable with the PE-90 then you will be over the cost of the PE-90 for the same features. The only add on that's more cost effective is the AR mag conversion. The PE-90 requires a new lower while the SL8 is a conversion kit.
Now the closest comparison in 21st century rifles would be the FS2000 vs the TAR 21 (Tavor).
Which brings us to an interesting point. A potential project of mine some day is to get another Tavor and have a 20" SS 1:7 5R rifled bull barrel put on it. That with the bottom rail for the handguard to add a bipod I think would be one heck of a fun semi auto target/varmint rifle. Some day. Also the micro Tavor might provide some interesting things.
Other options are the ACR. But availability is pretty much non existent and frankly the firearm still seems to be in a beta stage as they continue to change things.