I build a bunch of systems with the Tyan board. When people came to me to build a system (when the PIII was still king) & they were not extremely computer saavy (hardware wise) or needed something extrememly stable (CAD machines, small business servers, etc..), I'd use the Tyan board for them because of the stability (I never found a BX or i815 board more stable than the Trinity 400). For people who wanted to overclock & play around, I usually used an Abit VT6X4 (or VH6) since the Tyan board is not a good overclocker.
Back then I was mostly using voodoo 3 cards, TNT2's or GeForce 256 cards. I never used an ATI card till last year (Until the Radons, there were no ATI cards I liked well enough to use & they never had decent drivers till just recently). The Abit & Asus boards would generally give a little better performance in benchmark programs (not noticible in real world applications), but for most people the extra stability was worth it. I do not think I ever used a PCI video card in one. I'd guess I built 20-25 systems with the Tyan board, 5-6 with the P3V4X, and 10-12 on the Abit VT6X4 (& VH6 -- socketed version). My main rig back then had each of them in it at one time or another (I had the Trinity 400 first, switched to the P3V4X, then to the VT6X4. That was still my main machine till a few months ago till I went to an XP 1700 DDR system -- I was getting jellous that every machine I built for other people blew mine out of the water.) The reason I switched away from the Tyan board is that I got into hardcore overclocking & needed a board that could do it. As good as the P3V4X was, I found that the Abit VT6X4 was much better. The 2nd ISA slot was also a added benefit since I had a hardware modem & a soundblaster AWE64 gold soundcard. Since the KT133a chipset came out(and now the KT266a & KT333), I mostly build Athlon systems now (best price/performance ratio now), so I have not built a new PIII system on one of these boards for about a year and a half or so. I have occasionally picked some up on the used market & build inexpensive 'budget boxes' on them (again, no higher end video cards). I think the higeset end video card I have put in one is a GeForce 2 GTS DDR.
One 'quirk' that board has with the AGP controls is that you had to manually set the AGP driving value to 'CC' in the BIOS for best performance (this per the Tyan website). I think later BIOS revisions have corrected this.