I don't use these filters but once a season on my 1000's, then replace with new ones so I've never had a problem, I've personally have used over 200 in the last 6 years. (I only broke a couple by making the lines to tight and bent the ends)
I know some of my customers have come back in for service 2-3 years later and still running these filters and no problems at all. I don't think that this company that makes these ones have the problems your speaking of them coming apart... so it's your call.
Yes, use the TBM 1st, and go bigger with the prop...Scat-Trak 14-19 -3 big hub should help you get in the ballpark. I run bigger than that on my 8mm strokers and no problems with the TBM. Start with the medium cone as they come with 3 cones! This way you can tune either way.
Are you running a bored out nozzle?
Now if cost is no problem...order a new billet mag pump Monday as you won't beat the performace that a Skat-Trak Magnum pump gives you!