Up until a couple of years ago i seemed to buy just about anything that took my fancy. Certainly in 2016/17 we spent more than we should have on our films as we also ventured into 16mm in a much bigger way.
This year we took a bit of a breather and looked at what we had spent. It woke me up a bit, A fair amount came from normal income but since March 2017 we took a real look at our two collections which went way over the 600 mark. It looked as though we, (me in particular), were becoming hoarders of films rather than collectors. The only reason for going back into 16mm was after chatting to various people within the hobby via emails. It was very clear that titles i really wanted were on that format for good prices and that super 8 titles were starting to become ridiculously expensive for the same titles i wanted. Aside this, i love the quality of decent 16mm prints and the titles that come up.
As my Brother is now into his 60s and i myself into my later 50s, we took a conscientious decision early this year to start to reduce our 8mm collection in order to fund the hobby and to reduce the numbers. Again, speaking to other people in the hobby it seems to be the sensible thing to do. It makes the hobby self funding but also prevents reels of film building up that only get viewed once & space wasted in the film room. The other reason for the downsize is to rid our collections of fading prints, clearly i wont want to sell off all of them but certainly run of the mill titles have gone and others to follow. It has to be said that while i was reluctant to let some of them go, (assault on precinct 13 and National Lampoons animal house), these prints are just no longer the same as when they were in there glory years. One of the two titles fetched me over a 100 pounds, that bought me a superb print on 16mm and with change left. Also two 2 minute films on two reels have literally paid for my copy of Mississippi Burning which is uncut, LPP and stunning in condition. The up side is that by moving these on other collectors will continue to enjoy them as we have.
The funny is that today i took another look through my own collection, it's too way too big now and what ive sold doesn't seem to have made much of a dent. You certainly have to be very ruthless, its too easy to pick one up and say, "no not yet". I've done that a few times.

As far as the 16mm's are concerned, i have been a good boy and kept it to well below 30, again, i have moved one or two on, generally, anything with fade, at present i have put up a minder episode on flea bay, i'd love to keep everything but in order to to have quality, the quantity must go.

Any thoughts?

wait till you have 4 thousand features like me

I tend to buy 16mm as Super 8 has seen ever increasing prices lately. I suppose I have most of the Super 8 that I want having bought them over the years.
Having said that, I have in the last week bought a Super 8 cartoon, a 9.5mm sound musical, and a 16mm short and a TV show.
Also, I much prefer handling 16mm, as in the past I did mobile and ran a film society.
But, as an ex cinema projectionist, there's nothing like 35mm .

My collection has remained small by just seeking out very specific titles. I particularly like rare live action shorts in scope or authentic cinema daysets/ads etc. That policy also helps my wallet.

My dream is to get my 4K digital home cinema set up and run my movie nights again, but this time with a Super 8 or 16mm pre-show, which will include ads and sometimes a good colour cutdown or short.

I didn't realise Super 8 could look so good until I got a 1.1 Schneider lens and started to buy some Derann 'golden years' items. The two combined make for a sometimes spectacular image. I also think the demos at BSTR and other shows are amazing with a GS1200 projected onto a 12-foot or greater screen. 16mm is just too space-hungry and until I get a bigger place, I'm going to have to limit my choices on that format to only much-desired titles.

David, Sounds like your pension pots sorted

Tom,
I think the adjustments you and your brother have made re: film collecting in the last year or so make good sense.
I do really like the idea of at least partially or mostly "self-funding" film purchases by moving on some titles that are no longer watched/desired. With only a few exceptions, I am also looking to move out most of my Eastman's and SP's that are slightly faded pink or orange. If, over time, I can get the collection to be almost all low-fade (and B&W), then the only big worry that remains is vinegar syndrome. Mylar/estar copies, where possible, help eliminate the risk of VS to the collection as well.

I will add more Super 8 and 16mm titles, but will try and do so without always expanding the collection. I have a few hundred titles and for me at least, I can always find something in the stacks that I want to watch. I am glad there are collectors with more robust collections, and wish I could be one of them with thousands of interesting and rare titles but it is not to be for me.

I also have a 35mm Simplex E-7 projector and a couple of films, but the projector isn't set up yet with the sound amps, processor etc., and I will probably be ending that gauge entirely and selling off, rather than investing more money into getting it situated. It is interesting though, how some newer 35mm titles with great color etc seem to go for less than I would think a Super 8 or 16mm print of the same title would.....