Yep, my speeders, BEEPS, the Trackmobile, Wienermobile etc. all have issues with the DSS or the long curved switches, even with the relays installed. When I investigate, I see the rollers firmly sitting on a powered rail, but only one wheel without a tire near a powered rail, and apparently that one wheel loses contact long enough to stop the presses. The relays did help some paths through the switch, but not consistently. Larger stuff that was stalling on the DSS passage are now making it across, but that doesn't help the little guys.
As for making them available, I was looking and having issues finding the relay I used. I have my stock of the relays I used, but they're out of stock. As for a thru-hole design, I also try to use parts I've already used in another design to minimize the number of parts I have to keep around. It's already getting hard to keep up with all the parts now. Taking time to design another board that I'll never build and having to verify the design all takes time.
Maybe it's time you stepped up to some simple SMT designs and tried your hand at building them. 
Oh, OK, here's what a thru-hole version would look like. You still have to contend with the opto, I didn't find one that matched what I needed in thru-hole. It gets a little bigger at 1.3" x 1.05" of course.
