EdricBF

Keep the Pen-F, IMHO, and see if you can enjoy a fixed-focal length lens, no IBIS camera like the X100. If you use the Pen-F with only one fixed lens and IBIS is not important, then it is a no-brainer...

Having Fuji, Olympus and Sony, I would advise you to try an Olympus body: its IBIS technology is fantastic and would allow you to put that "extra-shake" behind your concerns. Or, if you really want to go Fuji, I guess you would be very happy with a 2nd-hand X-H1 (I had one and replaced it with an X-T3): it is heavier and the IBIS is also great. But I'd check the Olympus before anything...

I have had problems with two copies of the 18-135: I could not have good focus away from the central area of the frame at apertures below f/11. Got rid of the lens but was convinced that I got a bad sample, since so many people praised the thing. A year later decided to give it another try, but the results were the same as before, like the focus plane was uneven/slightly warped except for the central area at f/5.6 and f/8. I have never used a superzoom because of such well known limitations, but I expected Fuji to come with something better: I wasn't lucky like some people that vow for it.

Sold my X-H1 for the X-T3, after realising that, for me, IBIS was not that necessary, the bulk was comparable to my Nikon D750 and I was kinda annoyed when Fuji launched the X-T3 soon after I purchased the H...

The one and only occasion I thanked for the "splash resistance" of my (ex-) X-T1 was when I spiiled milkshake over it: after my initial shock I removed battery and card and shook it under a faucet (low water pressure) to "dilute" and remove the milkshake... Left to dry and later in the day it was working perfectly, although milkshake did got into the recesses and under the dials...

I gave up my D750 just because of its bulk and weight with FF lenses, despite being the most compact FF Nikon. Tried m4/3 for some time and found Fuji the ideal bulk/IQ/useability to me. Although my X-T2 provides great IQ, the D750 was the best camera that I have owned since old days with a Nikon FM2n: from birds in flight to sports to kids running etc etc it never missed a shot using the Group Area AF under CAF, and its low light capbilities result in great pictures under many situations. Even family pictures taken with the integrated flash were excellent IMHO. The X-T2 is, for me, is the "next-to-D750 big thing": it has a good Group AF, turns out excellent images but falls short comparing to the D750. If size/weight were not such an important issue, I'd go back to the D750 immediately...

I consider my 16-50 II images a tad better than the ones taken with my 18-55, but when I am going to shoot something important (i.e. travel) I always reach for the latter. The 18-55 aperture ring, IS on/off button and construction makes it feel way more reliable and useable to me...

BBF in DSLRs is great (I have a Nikon D750), but I never managed to really trust it in my mirrorless cameras (Panas, Olys and Fujis) for the reasons well pointed out above...

I was so disappointed with my TWO copies of the 18-135 (first one brand new, even sent to Fuji to check, the second one to confirm it was that bad...) that now I filter the reviews checking the reviewer's opinions (if any...) on that lens. Seems that people only care about the center, but for anything landscape or wider below f/8 off-center, the 18-135 sucks!!! Any 18-55, 16-50, 18, 27 etc. "mops the floor" with it. No wonder Fuji puts an excellent IS system on it, so you can keep f/11 and high ISO most of the time... But I have seen several positive opinions, so mileage varies, of course...

I would like to add that both my copies were great at F/11, and the IS helped a lot to keep that aperture. Unfortunately, many times I had to open up to F/5.6 and the landscape/interior results were, for me, a disappointment. For those "once in a lifetime trips", I'd rather not risk...

I don't like the 18-135, had two copies and got rid of both: below f/8 at any focal length just the center was sharp, a bad thing for landscapes. I purchased the first one brand new as soon as it was launched, and after a few shots I couldn't believe the lack of sharpness off-center. Sent it to Fuji and it was returned with a "no problem found" note. I assumed that the problem was the Fuji representative lab and sold the thing. One year later I purchased another, this time used with a good price, and got the same results. I know superzooms are not so good, but I expected more from that Fuji. Sold it with a disappointed heart...

My 18-135 is a disappointment for anything away from the center below f/8 or f/11... "Convenience" is the word for my copy, unfortunately, what makes me compose considering cropping away the laterals if for some reason I have to keep the aperture below f/8...

I really don't like my 18-135: anything away from the center below f/8 or f/11 is a disappointment in terms of IQ...

But its size/weight doesn't really matter, IMHO, if you are on a LandRover in the bush... On the other hand, Fuji allows cropping reasonably, and a 55-200 or a 50-230 would bring good pictures anyway. Been to SA a couple of years ago, and the animals come and go so often and so close that I craved for a superzoom like the 18-135. Later I purchased that lens but the copy I have doesn't show good IQ away from the center below f/8 at all focal distances.

I use the XC 16-50 for its compactness, reasonable IQ and IS, and the 27/2.8 for its (IMHO) fantastic crispness @f/8 and beyond. My 18-135 is getting dust, since its IQ off-center is, for me, unacceptably bad below f/11 at all focal lengths...