I am blessed to have excellent samples of both the TEC 140ED and the TEC160ED. Both are optically superb. I've made extensive side-by-side comparisons.
I personally find the larger aperture a noticeable advantage visually. The 14% resolution increase of the 160 over the 140 is most of the time, with the seeing around here, subtle, but important to me. The extra 30% light grasp is less subtle for me. Seeing permitting, those combined advantages of the larger aperture means stuff that is at the threshold of detection in the 140ED is easily seen in the 160ED. I just see more stuff in the larger scope..imagine that.
My sample G11 (with improved clutch pads) does just fine with both scopes, in fact, this G11 seems to prefer the extra weight of the 160ED. After a nudge on the diagonal, thing dampen out in about 1/2 second.
Speaking of weight, as configured in the pictures, from the G11's saddle on up, the 140ED and the 160ED weigh 30 and 35 pounds respectively. Which for me, right now, age 66, is an easy lift into the saddle.
The 160ED is an F8 (so it is 6" longer than the FL), is discontinued, and scarce on the used market, but, if you can find one goes for $7000 to $8000. The 140ED is much easier to find on the used market, going for $4800 to $5500. Both depending on condition and included stuff.
In extensive comparisons between my 140 ED and a new 140FL that I published here, I found little to choose between them, except the 140ED had a slightly "cooler" color "tone".
I can't comment on Dobs.
So I hope this bit of a data dump helps you out and good luck. I'm glad you're doing this for yourself.