Make sure you post your impressions of using that Leitech device. I have a DPS-290, which isn't really the same thing, but some people use it for noise reduction. Some people swear by it, but I wasn't crazy about it in my setups. I'd imagine it probably won't make too much of a difference on laserdiscs, but the time base correction will probably do wonders for color on VHS.
I also have a Dvdo VP50 (but not the pro model.) The thing is great for upscaling to a widescreen set. I think the pro model has noise reduction too, but I'm not sure if it's anything useful for laserdiscs. I upgraded to the Dvdo Duo, which is really similar but it has a much better comb filter for composite sources and it auto switches 8 ports on HDMI, which I'm using much more than I would have thought beforehand.
That said, your Sony tube is badass. Laserdisc may look best simply connecting composite directly in without any processing equipment.