High employer retirement contribution — where should extra savings go?

I’m 27 and make ~$95k/year. My employer automatically contributes 14.2% into a 401(a) (no match required). I also contribute 8% pre-tax into a 403(b). I just paid off my car and now have ~$2,500/month extra. No credit card debt. Federal Student loans ~$39k at 4.6%, currently paying $400/month (minimum). I currently rent a cheap place, but may want to buy a house in the future and am considering a Roth IRA since contributions can be withdrawn for a down payment. I am not currently on the high deductible health plan for a HSA but will be changing next enrollment. Question: Is my pre-tax retirement exposure too high given the employer 401(a)? Should I reduce the 8% 403(b) and redirect to a Roth IRA and/or taxable brokerage, or keep everything pre-tax? Looking for guidance on how to best allocate the extra cash.