I read Syl Arena's Speedliter's Handbook recently and he says, I believe, that he has 12 speedlites, and his mentor Joe Mcnally, has 17. You get when you need, I don't think there is such a thing as too many...
Can you imagine the attention to detail required setting up 12 let alone 17 Speedlights? And the lack of flexibility? For certain projects you'd certainly get a unique look.
For OP Quasimodo, of course it depends on the sort of projects you'll be taking on. A bunch of Speedlights might be perfect for your work. If you're not missing the Elinchroms, then maybe you don't need monos. If future projects require you do need monos again, Einsteins are worth a very close look. I have six of them plus a raft of accessories, modifiers, VML batteries etc. The PCB stuff is extraordinary value. http://paulcbuff.com/
For HSS work, at a pinch I can get the Einsteins to play ball triggering them with the almost mythical abilities of the Phottix Odin system and their ODS fine-tuning function. Only expect HSS/Einstein to work on full power (longest flash duration). More flexible for HSS, and maybe very useful for you, is the Godox Witstro 360, also triggered with Phottix Odin. There is a $25 eBay accessory that means you can use Bowens mount modifiers. http://flashhavoc.com/godox-witstro-ad180-ad360-review/
With the Phottix Odins you can maximise HSS output with ODS fine tuning. Rather than going right into ODS here, check out:http://flashhavoc.com/phottix-odin-ods-over-drive-sync/comment-page-1/#comment-19555
Phottix is doing great things right now. Their Mitros speedlight is getting a lot of attention as is their most recent announcement, the TTL & HSS capable Indra 500 http://flashhavoc.com/phottix-indra500-ttl-announced/
But how many speedlights are enough? For Joe Mcnally and his required team of lighting assistants, seventeen is good. For me it's two 600 EX-RT's plus the Godox Witstro 360. I'd say build up as projects demand and budget allows.