I was seriously considering one, but the next set of tyres I got (folding Maxxis; On-One Smorgasbord & Chunky Monkey) went up with the trackpump alone. I had built up the rim cavity with some duct tape and this snugged the bead down. This combined with schraeder valves cut from old tubes worked better than rubber rim strips (they need to have the threaded stem and lock nut like a presta). The bead didn’t sit properly due to the lump at the valve on the strips but it can with the separate valve.
That aside, have you tried with the valve core removed?