The trouble with both being on the same planet is, there are not enough tiles to include both the Omega Research with the Tech Capital, and the Manufacturing Capital on the same planet.
I don't bother with these anymore. There is no real long term benefit to a true uber research planet. I view these buildings as waste of a tile because I can't later build a stockmarket on top of my tech cap, etc. By the end of the second game year I can gaurantee you that I will have stockmarkets built over all these bonus tiles including both precursor tiles.
The only benefit these have to me is early on in the colony rush and the only purpose of an early production planet like this is to be able to quickly build early wonders like the MCC, ASC and SCC and to be able to build a colony ship per turn. I have no need of any research buildings anywhere after the first two years of the game and my need for production probably doesn't last even that long.
Usually I consider my home planet a throw away planet that simply gets clogged up with early wonders. Late game wonders I simply buy and place on PQ4's. If I won't waste a tile on global research wonders like hyper computers or nano recorders I certainly won't waste a tile on a tech cap or omega research center that only gives a benefit to the planet its on. I will use the manu cap on my home planet if I have a poor starting planet that needs the boost to be able to produce a colony ship per turn, but like I said I consider my home planet a throw away planet most games.
I get my research more from the initial colony buildings on 400 planets than from any combination of research buildings, bonus tiles and research bonus buildings. I get my production by directly buying ships from an income of 1.3+ million bc's per week as opposed to actually producing them with industry.
By the time I conquer 100 AI planets (this is a gigantic galaxy game) all I will be building is stockmarkets on every tile of every planet. And I will have probably conquered 100 AI planets before the end of year 0, certainly by April of year 1. I may not get around to over building the factories and labs on my two starting planets until the end of year 1 but they certainly won't see new years day of year 2.
Hey Mumble send me a save game I know you save it i want to play with it !!
Sure Nasty.

I'll PM you at the Core.