I don't know of a difference but there may in fact be some small difference.
The 2510P uses 3 Z16 transmission line tweeters, one 4 ohm, two 8 ohm. The S-150P only has one 4 ohm Z16, the two 8 ohm drivers are Z11 non-transmission line tweeters.
EDIT*** immortal sound messaged me the other day after asking Ken (Kriesel) about this... as I mention above and elsewhere... my info at the time was derived from paperwork from VIFA (not M&K)... it must have gotten messed up somewhere between the two companies (or between VIFA and my old company). Anyways, Ken is now "on record" as stating that both powered versions (S-150P & MPS-2510P) are identical with all 3 tweeters being Z16 transmission line versions of the tweeter, not as I've stated above. So in review, this would mean that all passive versions (150 or 2510) would have one (center) Z16 transmission line and two (top & bottom) Z11 non-transmission line tweeters (resistance ratings are correct as stated and explained). While both powered versions use only Z16 transmission line tweeters (ohm ratings as previously stated). (sorry about the confusion... just going from what documentation I had at the time; this does make sense though)
Yes, I liked the one I built too, I like the smoked plexi look but I don't think I can cut it with a water jet like the metal face plate I'm doing. The 5100 had 2 Vifa P/N P830769 (17037); at least for a time according to paperwork I have. I'm considering getting more from Vifa, but of course they won't have the M&K logo on them. I don't know the exact difference between the 17035 and the 17037, could be just the manufacturer or an actual design change. I don't think the 17035's that Mavin has came from Vifa originally; The 17035's should have enough power handling to work with a 400 watt amp (but I haven't tried it yet). How much difference in interest would people have in the different options I have for building these subs?
1- MX-2500 hybrid with 17035's with M&K logo
2- MX-2500 hybrid with 17037's from Vifa with no logo
3- MX-2500 hybrid with the Hamster Audio driver
Thanks for the input...
p.s. I fixed the gasket links today, sorry about that...